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).

1 files changed, 3 insertions, 0 deletions

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