fix(zsh): make compdef guard check completion fn, also wire nix-profile fpath

Previous guard checked `$+commands[Y]` (binary present in PATH), but the
`compdef: unknown command or service: Y` message comes from compdef when
the *completion function* `_Y` isn't registered — on the remote-dev VM
`systemctl`, `just`, `lsd` are all on PATH yet zsh has no `_systemctl`
because Ubuntu's system zsh doesn't include nix-profile's
share/zsh/site-functions in fpath.

Two-part fix:
1. Prepend $HOME/.nix-profile/share/zsh/{site-functions,vendor-completions}
   to fpath (when they exist) before compinit, so the completions get
   loaded on the VM the same way they do on Arch.
2. Switch the compdef guard to `$+_comps[Y]` — the assoc-array compinit
   actually populates with every command that has a registered completion
   handler. Still belt-and-suspenders in case something ships a binary
   without a matching completion file.

0 files changed, 0 insertions, 0 deletions