fix(nix): parameterize dotfiles path per profile; rename dockerfile LSP

- common.nix hardcoded the runtime dotfiles checkout to
  ~/.local/share/dotfiles, which is correct for the remote-dev VM but
  not the Arch host (where the canonical clone lives at ~/dotfiles).
  ssh activation was failing with 'cannot stat
  /home/sommerfeld/.local/share/dotfiles/private_dot_ssh/config' on
  every host nix-switch.

  Promote the path to a typed option (config.my.dotfilesPath) and set
  it from each profile:
    nix/host.nix -> $HOME/dotfiles
    nix/vm.nix   -> $HOME/.local/share/dotfiles
  common.nix now wraps its config in 'config = { ... }' so the
  options can sit alongside.

- dockerfile-language-server-nodejs was renamed in nixpkgs to
  dockerfile-language-server; pick up the new name to silence the
  evaluation warning (the rename will eventually become a hard error).

3 files changed, 26 insertions, 2 deletions

diff --git a/nix/common.nix b/nix/common.nix
index 217d335..a34dfba 100644
--- a/nix/common.nix
+++ b/nix/common.nix
@@ -5,6 +5,10 @@
 # host and the Ubuntu remote-dev VM. Profile-specific extras live in
 # `host.nix` and `vm.nix`.
 #
+# The path to the runtime dotfiles checkout (where symlinks point) is
+# read from `config.my.dotfilesPath`; the per-profile module sets it
+# (host: ~/dotfiles, vm: ~/.local/share/dotfiles).
+#
 # Policy: this profile carries leaf CLI tools, editor/AI-agent runtimes
 # (node, uv), and build *orchestrators* (cmake, ninja, ccache, sccache).
 # It must NEVER carry actual compilers or linkers — those would shadow
@@ -27,10 +31,21 @@
 # system python3).
 
 let
-  dotfiles = "${config.home.homeDirectory}/.local/share/dotfiles";
+  dotfiles = config.my.dotfilesPath;
   link = path: config.lib.file.mkOutOfStoreSymlink "${dotfiles}/${path}";
 in
 {
+  options.my.dotfilesPath = lib.mkOption {
+    type = lib.types.str;
+    description = ''
+      Absolute path to the runtime dotfiles checkout that the
+      mkOutOfStoreSymlink-based home.file entries point at. The host
+      profile sets this to "$HOME/dotfiles"; the vm profile sets it
+      to "$HOME/.local/share/dotfiles".
+    '';
+  };
+
+  config = {
   home.stateVersion = "25.05";
 
   # ── Packages ────────────────────────────────────────────────────────────────
@@ -148,7 +163,7 @@ in
     autotools-language-server
     basedpyright
     bash-language-server
-    dockerfile-language-server-nodejs
+    dockerfile-language-server
     just-lsp
     lua-language-server
     neocmakelsp
@@ -250,4 +265,5 @@ in
 
   # ── Enable HM-managed activation messages ──────────────────────────────────
   programs.home-manager.enable = true;
+  };
 }
diff --git a/nix/host.nix b/nix/host.nix
index 7d81ffe..d589002 100644
--- a/nix/host.nix
+++ b/nix/host.nix
@@ -9,6 +9,11 @@
   home.username = builtins.getEnv "USER";
   home.homeDirectory = builtins.getEnv "HOME";
 
+  # The Arch host keeps its chezmoi source state at ~/dotfiles (the
+  # canonical clone location for the dotfiles repo). The VM convention
+  # of ~/.local/share/dotfiles doesn't apply here.
+  my.dotfilesPath = "${builtins.getEnv "HOME"}/dotfiles";
+
   # ── Smartcard (Yubikey) ────────────────────────────────────────────────────
   # Nix's gnupg ships its own scdaemon. Delegate to the system pcscd
   # service instead of letting nix's scdaemon open the USB device
diff --git a/nix/vm.nix b/nix/vm.nix
index 7445b7b..257436e 100644
--- a/nix/vm.nix
+++ b/nix/vm.nix
@@ -10,6 +10,9 @@
   home.username = builtins.getEnv "USER";
   home.homeDirectory = builtins.getEnv "HOME";
 
+  # Remote-dev VM clones the dotfiles tree under XDG_DATA_HOME.
+  my.dotfilesPath = "${builtins.getEnv "HOME"}/.local/share/dotfiles";
+
   home.sessionVariables = {
     # Ubuntu 20.04-derived hosts still default to cgroups v1; podman 5
     # warns on every invocation. Flipping to v2 is a host-level reboot