refactor(nvim,zsh): remove Mason; use Home-Manager-provisioned tooling

LSPs, formatters, linters, and the lldb-dap debugger now come from
~/.nix-profile/bin (see nix/common.nix). lspconfig keeps the default
configs; we just opt-in via vim.lsp.enable() with an explicit list.

Changes:
  - dot_config/nvim/lua/plugins/lsp.lua: drop mason*, replace
    mason-lspconfig handler with explicit vim.lsp.enable({...}); drop
    groovy/jenkins formatters and lint entries; drop systemd lint
    (nginx + groovy + systemdlint tools dropped per plan).
  - dot_config/nvim/lua/plugins/debug.lua: drop mason-nvim-dap; drop
    codelldb adapter; switch dap.configurations.cpp to type='lldb'
    (lldb-dap is the upstream successor, ships with pkgs.lldb).
  - dot_config/nvim/init.lua: remove mason.nvim, mason-lspconfig.nvim,
    mason-tool-installer.nvim, mason-nvim-dap.nvim from vim.pack.add.
  - dot_config/nvim/lua/config/update.lua: remove MasonToolsUpdateSync.
  - dot_config/zsh/dot_zshrc: flip plugin source order — prefer
    ~/.nix-profile/share, fall back to /usr/share/zsh (was the other
    way around).
  - nix/bootstrap.sh: drop the uv-python3.11 step (no longer needed
    once Mason no longer source-builds Python LSPs on Ubuntu 20.04).

Phase 6 of the nix-on-host migration plan.

6 files changed, 40 insertions, 126 deletions

diff --git a/dot_config/nvim/init.lua b/dot_config/nvim/init.lua
index 32873d3..7559556 100644
--- a/dot_config/nvim/init.lua
+++ b/dot_config/nvim/init.lua
@@ -68,9 +68,6 @@ vim.pack.add({
   gh("folke/lazydev.nvim"),
   gh("neovim/nvim-lspconfig"),
   gh("j-hui/fidget.nvim"),
-  gh("williamboman/mason.nvim"),
-  gh("williamboman/mason-lspconfig.nvim"),
-  gh("WhoIsSethDaniel/mason-tool-installer.nvim"),
   gh("stevearc/conform.nvim"),
   gh("mrcjkb/rustaceanvim"),
   gh("mfussenegger/nvim-lint"),
@@ -80,7 +77,6 @@ vim.pack.add({
   { src = gh("miroshQa/debugmaster.nvim"), version = "dashboard" },
   gh("mfussenegger/nvim-dap"),
   gh("theHamsta/nvim-dap-virtual-text"),
-  gh("jay-babu/mason-nvim-dap.nvim"),
 
   -- Runner
   gh("stevearc/overseer.nvim"),
diff --git a/dot_config/nvim/lua/config/update.lua b/dot_config/nvim/lua/config/update.lua
index bc7ee3d..7910dee 100644
--- a/dot_config/nvim/lua/config/update.lua
+++ b/dot_config/nvim/lua/config/update.lua
@@ -1,10 +1,10 @@
 -- Update orchestrator. Invoked from the justfile via:
 --   nvim +'lua require("config.update").run()'
 --
--- Cleans orphan plugins, applies plugin updates without prompting, then
--- runs :MasonToolsUpdateSync. Run interactively (not --headless) so the
--- diff buffer that vim.pack.update opens is actually visible — that
--- buffer IS the changelog. Quit manually with :qa once reviewed.
+-- Cleans orphan plugins then applies plugin updates without prompting.
+-- Run interactively (not --headless) so the diff buffer that
+-- vim.pack.update opens is actually visible — that buffer IS the
+-- changelog. Quit manually with :qa once reviewed.
 
 local M = {}
 
@@ -34,9 +34,6 @@ function M.run()
 
   print("[pack] updating plugins…")
   vim.pack.update(nil, { force = true })
-
-  print("[mason] updating tools…")
-  vim.cmd("MasonToolsUpdateSync")
 end
 
 return M
diff --git a/dot_config/nvim/lua/plugins/debug.lua b/dot_config/nvim/lua/plugins/debug.lua
index bef0d1c..0d97713 100644
--- a/dot_config/nvim/lua/plugins/debug.lua
+++ b/dot_config/nvim/lua/plugins/debug.lua
@@ -22,11 +22,6 @@ dap.adapters.gdb = {
   args = { "--interpreter=dap" },
   env = get_env_vars,
 }
-dap.adapters.codelldb = {
-  type = "executable",
-  command = "codelldb",
-  env = get_env_vars,
-}
 
 local function get_program()
   local _program
@@ -53,8 +48,8 @@ end
 
 dap.configurations.cpp = {
   {
-    name = "codelldb Launch",
-    type = "codelldb",
+    name = "lldb-dap Launch",
+    type = "lldb",
     request = "launch",
     cwd = "${workspaceFolder}",
     program = get_program,
@@ -68,8 +63,3 @@ dap.configurations.c = dap.configurations.cpp
 dap.configurations.rust = dap.configurations.cpp
 
 require("nvim-dap-virtual-text").setup({})
-require("mason-nvim-dap").setup({
-  automatic_installation = false,
-  handlers = {},
-  ensure_installed = {},
-})
diff --git a/dot_config/nvim/lua/plugins/lsp.lua b/dot_config/nvim/lua/plugins/lsp.lua
index a2a4036..5039d04 100644
--- a/dot_config/nvim/lua/plugins/lsp.lua
+++ b/dot_config/nvim/lua/plugins/lsp.lua
@@ -8,66 +8,30 @@ vim.lsp.enable("just")
 pcall(vim.lsp.enable, "tblgen_lsp_server")
 
 require("fidget").setup({})
-require("mason").setup({})
-require("mason-lspconfig").setup({
-  ensure_installed = {},
-  automatic_installation = false,
-  handlers = {
-    function(server_name)
-      vim.lsp.enable(server_name)
-    end,
-  },
-})
-require("mason-tool-installer").setup({
-  ensure_installed = {
-    "actionlint",
-    "autotools-language-server",
-    -- basedpyright: provided by the system pkg manager (basedpyright-bin from
-    -- AUR on Arch, pkgs.basedpyright in remote-dev/home.nix on the VM). Mason's pypi
-    -- distro pulls `nodejs-wheel-binaries` whose Linux wheels are only
-    -- manylinux_2_28; uv's standalone python (manylinux2014) rejects them and
-    -- pip falls back to building Node from source, which fails on Ubuntu
-    -- 20.04's gcc 9.4 (<10, no -std=gnu++20). lspconfig finds it on PATH.
-    "bash-language-server",
-    "clangd",
-    "codelldb",
-    "codespell",
-    "css-lsp",
-    "dockerfile-language-server",
-    "gh",
-    "gh-actions-language-server",
-    "groovy-language-server",
-    "hadolint",
-    "html-lsp",
-    "jq",
-    "json-lsp",
-    "jsonlint",
-    "just-lsp",
-    "lua-language-server",
-    "markdownlint",
-    "mdformat",
-    "neocmakelsp",
-    "nginx-config-formatter",
-    "nginx-language-server",
-    "npm-groovy-lint",
-    "prettier",
-    "ruff",
-    "rust-analyzer",
-    "selene",
-    "shellcheck",
-    "shellharden",
-    "shfmt",
-    "stylelint",
-    "stylua",
-    "systemd-lsp",
-    "systemdlint",
-    "taplo",
-    "typescript-language-server",
-    "typos",
-    "yaml-language-server",
-    "yamllint",
-    "yq",
-  },
+
+-- LSPs come from Home-Manager (see nix/common.nix). lspconfig ships the
+-- default configs; we just opt-in per server. (Previously this was driven
+-- by mason-lspconfig handlers; phase p6 of the nix migration removed
+-- Mason entirely.)
+vim.lsp.enable({
+  "autotools_ls",
+  "basedpyright",
+  "bashls",
+  "clangd",
+  "cssls",
+  "dockerls",
+  "eslint",
+  "gh_actions_ls",
+  "html",
+  "jsonls",
+  "lua_ls",
+  "neocmake",
+  "ruff",
+  "rust_analyzer",
+  "systemd_ls",
+  "taplo",
+  "ts_ls",
+  "yamlls",
 })
 
 vim.api.nvim_create_autocmd("LspAttach", {
@@ -194,11 +158,9 @@ require("conform").setup({
     bash = { "shfmt" },
     cmake = { "cmake_format" },
     css = { "prettier", "stylelint" },
-    groovy = { "npm-groovy-lint" },
     html = { "prettier" },
     javascript = { "prettier" },
     typescript = { "prettier" },
-    jenkins = { "npm-groovy-lint" },
     json = { "jq", "jsonlint" },
     jsonc = { "prettier" },
     just = { "just" },
@@ -230,12 +192,9 @@ local lint = require("lint")
 lint.linters_by_ft = {
   css = { "stylelint" },
   dockerfile = { "hadolint" },
-  groovy = { "npm-groovy-lint" },
-  jenkins = { "npm-groovy-lint" },
   json = { "jsonlint" },
   markdown = { "markdownlint" },
   makefile = { "checkmake" },
-  systemd = { "systemdlint" },
   yaml = { "yamllint", "yq" },
   ghaction = { "actionlint" },
   zsh = { "zsh" },
diff --git a/dot_config/zsh/dot_zshrc b/dot_config/zsh/dot_zshrc
index b227c8f..f94b82e 100644
--- a/dot_config/zsh/dot_zshrc
+++ b/dot_config/zsh/dot_zshrc
@@ -418,7 +418,8 @@ _fzf_compgen_path() { fd --hidden --follow --exclude ".git" . "$1" }
 _fzf_compgen_dir()  { fd --type d --hidden --follow --exclude ".git" . "$1" }
 
 # ── Plugins (must be sourced last) ────────────────────────────────────────────
-# Plugin locations: Arch system path first, ~/.nix-profile fallback for VM HM.
+# Plugin locations: ~/.nix-profile (Home-Manager) first, Arch system path as
+# fallback for un-bootstrapped states.
 _source_first() {
 	local f
 	for f in "$@"; do
@@ -432,17 +433,17 @@ ZSH_HIGHLIGHT_HIGHLIGHTERS=(main brackets pattern)
 typeset -A ZSH_HIGHLIGHT_STYLES
 ZSH_HIGHLIGHT_STYLES[comment]='fg=yellow'
 _source_first \
-	/usr/share/zsh/plugins/zsh-syntax-highlighting/zsh-syntax-highlighting.zsh \
-	$HOME/.nix-profile/share/zsh-syntax-highlighting/zsh-syntax-highlighting.zsh
+	$HOME/.nix-profile/share/zsh-syntax-highlighting/zsh-syntax-highlighting.zsh \
+	/usr/share/zsh/plugins/zsh-syntax-highlighting/zsh-syntax-highlighting.zsh
 
 _source_first \
-	/usr/share/zsh/plugins/zsh-autosuggestions/zsh-autosuggestions.zsh \
-	$HOME/.nix-profile/share/zsh-autosuggestions/zsh-autosuggestions.zsh
+	$HOME/.nix-profile/share/zsh-autosuggestions/zsh-autosuggestions.zsh \
+	/usr/share/zsh/plugins/zsh-autosuggestions/zsh-autosuggestions.zsh
 bindkey '^[[Z' autosuggest-accept  # Shift-Tab to accept suggestion
 
 _source_first \
-	/usr/share/zsh/plugins/zsh-history-substring-search/zsh-history-substring-search.zsh \
-	$HOME/.nix-profile/share/zsh-history-substring-search/zsh-history-substring-search.zsh
+	$HOME/.nix-profile/share/zsh-history-substring-search/zsh-history-substring-search.zsh \
+	/usr/share/zsh/plugins/zsh-history-substring-search/zsh-history-substring-search.zsh
 [[ -n "${key[Up]}"   ]] && bindkey -- "${key[Up]}"   history-substring-search-up
 [[ -n "${key[Down]}" ]] && bindkey -- "${key[Down]}" history-substring-search-down
 
diff --git a/nix/bootstrap.sh b/nix/bootstrap.sh
index 9f5e144..86f82ca 100755
--- a/nix/bootstrap.sh
+++ b/nix/bootstrap.sh
@@ -8,8 +8,7 @@
 #   1. Install Nix (Determinate Systems installer, multi-user).
 #   2. Clone (or fast-forward) the dotfiles repo to ~/.local/share/dotfiles.
 #   3. Run `home-manager switch --flake .../nix#vm`.
-#   4. Install python3.11 via `uv` (needed by Mason pip installs).
-#   5. Add Nix-store zsh to /etc/shells and chsh the user.
+#   4. Add Nix-store zsh to /etc/shells and chsh the user.
 #
 # Environment overrides:
 #   DOTFILES_REPO   Git URL (default: https://github.com/ruifm/dotfiles)
@@ -35,9 +34,6 @@ else
   log "Nix already installed, skipping installer."
 fi
 
-# ── 1b. (moved to step 4 — uv comes from the nix profile, only available
-#         after `home-manager switch`) ─────────────────────────────────────────
-
 # Source nix env for the rest of this script (installer writes
 # /etc/profile.d/nix.sh but the current shell hasn't sourced it).
 if [ -f /nix/var/nix/profiles/default/etc/profile.d/nix-daemon.sh ]; then
@@ -68,32 +64,7 @@ nix --extra-experimental-features 'nix-command flakes' \
   run home-manager/master -- \
   switch --impure --flake "$DIR/nix#vm" -b backup
 
-# ── 4. Mason's python interpreter (via uv from the nix profile) ──────────────
-# Mason installs some LSPs/linters into per-package pip venvs. We need a
-# python3.11 that:
-#   (a) meets Mason's >=3.10 version requirement (Ubuntu 20.04 ships
-#       /usr/bin/python3 = 3.8 — too old), and
-#   (b) accepts manylinux wheels (Nix's python rejects them by design;
-#       pip then falls back to compiling `nodejs-wheel-binaries` from
-#       source, which fails on the host's gcc 9.4 — needs C++20).
-#
-# `uv python install 3.11` fetches a portable CPython build (python-build-
-# standalone, manylinux-compatible) into ~/.local/share/uv/python/. We
-# symlink its `python3.11` into ~/.local/bin/ (already on PATH from
-# zprofile) so Mason discovers it. Does NOT shadow /usr/bin/python3 —
-# leaf-tools policy intact. Works on any distro/release, no PPA required.
-UV_BIN="$HOME/.nix-profile/bin/uv"
-if [ -x "$UV_BIN" ]; then
-  if [ ! -x "$HOME/.local/bin/python3.11" ]; then
-    log "Installing python3.11 via uv (required for Mason pip installs)…"
-    "$UV_BIN" python install 3.11
-    UV_PY311="$("$UV_BIN" python find 3.11)"
-    mkdir -p "$HOME/.local/bin"
-    ln -sf "$UV_PY311" "$HOME/.local/bin/python3.11"
-  fi
-fi
-
-# ── 5. chsh to nix-store zsh ─────────────────────────────────────────────────
+# ── 4. chsh to nix-store zsh ─────────────────────────────────────────────────
 NIX_ZSH="$HOME/.nix-profile/bin/zsh"
 if [ -x "$NIX_ZSH" ]; then
   if ! grep -qxF "$NIX_ZSH" /etc/shells 2>/dev/null; then