Assemble fish's interactive init in Nix, not at runtime

Fold the done plugin tuning back into config.fish and drop the conf.d
fragment: config.fish is read whole into interactiveShellInit, so Nix
assembles the interactive init at build time instead of fish autoloading
a separate conf.d file. functions/copy.fish stays a function file, the
idiomatic home for a lazily-autoloaded function.

.claude/tasks/0005-fish-shell-module.md

@@ -39,4 +39,4 @@ Configure the plugins natively through home-manager rather than a fish plugin ma
 - **Abbreviation-first.** Every non-eza alias is now a `shellAbbr` (the eza `ls` family stays an alias), `preferAbbrs = true`, and `generateCompletions = true` is pinned rather than left to the upstream default.
 - **vi command-line editing.** `interactiveShellInit` sets `fish_key_bindings fish_vi_key_bindings`; the `bang-bang` plugin re-binds `!`/`$` in insert mode via its own `--on-variable fish_key_bindings` handler, so the switch keeps them working.
 - **Trimmed aliases.** Navigation capped at four dots (`.....`/`......` dropped); `psmem`, `psmem10`, `dir`, `vdir`, and `please` removed.
-- **Module directory mirrors `~/.config/fish/`.** The Module lives at `modules/fish/fish.nix` with its hand-written fish laid out as in a real fish config: `config.fish` (interactive init, read into `interactiveShellInit`), `conf.d/done.fish` (the done plugin's tuning, placed as a real conf.d file via `xdg.configFile`), and `functions/copy.fish` (the non-trivial `copy` body, read into the `functions` option). Trivial one-liner functions stay inline in `fish.nix`. `completions/` and `themes/` are omitted because they have no content and git cannot track empty directories. The Auto-loader only collects `.nix`, so every `.fish` file is inert to it.
+- **Module directory mirrors `~/.config/fish/`.** The Module lives at `modules/fish/fish.nix` with its hand-written fish laid out as in a real fish config: `config.fish` (the whole interactive init, read into `interactiveShellInit`) and `functions/copy.fish` (the non-trivial `copy` body, read into the `functions` option). Trivial one-liner functions stay inline in `fish.nix`. Everything Nix assembles at build time — nothing of ours is autoloaded from a separate runtime file — so the `done` plugin tuning stays inside `config.fish` rather than a `conf.d` fragment (`conf.d` would only earn its name if fish autoloaded it at runtime). `functions/copy.fish` is the sole exception, because fish autoloads function files lazily and that is the idiomatic home for a function. `completions/`/`themes/`/`conf.d/` are omitted as they hold no content of ours and git cannot track empty directories. The Auto-loader only collects `.nix`, so every `.fish` file is inert to it.

modules/fish/conf.d/done.fish

@@ -1,3 +0,0 @@
-# Tune the done plugin: only notify for commands past 10s, at low urgency.
-set -g __done_min_cmd_duration 10000
-set -g __done_notification_urgency_level low

modules/fish/config.fish

@@ -8,6 +8,10 @@ set -gx VISUAL nvim
 set -x MANROFFOPT "-c"
 set -x MANPAGER "sh -c 'col -bx | bat -l man -p'"
 
+# Tune the done plugin: only notify for commands past 10s, at low urgency.
+set -g __done_min_cmd_duration 10000
+set -g __done_notification_urgency_level low
+
 # Prepend ~/.local/bin to PATH when it exists.
 if test -d ~/.local/bin
     fish_add_path ~/.local/bin

modules/fish/fish.nix

@@ -37,9 +37,6 @@ in
         wget # non-interactive HTTP downloader; backs the wget abbreviation
       ];
 
-      # done's tuning lives in its own conf.d snippet, mirroring ~/.config/fish.
-      xdg.configFile."fish/conf.d/done.fish".source = ./conf.d/done.fish;
-
       programs.fish = {
         enable = true;