fix(deps): demote cargo/starship to rec, remove fisher from catalog

Required tier is now fish, fzf, and zoxide only — the tools the config
meaningfully can't function without. Everything else degrades gracefully.

- cargo: only used by fish-deps to install Rust tools or build fish from
  source; all paths are already gated on type -q cargo
- starship: type -q guard in conf.d/starship.fish; shell falls back to
  fish's built-in prompt without it
- fisher: auto-bootstrapped by first_run.fish; no need for users or
  fish-deps to manage it. Remove from catalog and clean up the now-dead
  fisher-bootstrap/special-fisher installer cases.

Catalog arrays verified aligned at 26 entries each.

docs/fish-config.md

@@ -850,11 +850,11 @@ Add -i (interactive confirmation) to destructive commands:
 
     Dependencies are grouped into three tiers:
 
-      Required      cargo, fish, fisher, starship, fzf, zoxide
+      Required      fish, fzf, zoxide
       Integrations  wakatime, tailscale
-      Recommended   uv, direnv, paru, yay, eza, lsd, bat, btop, dust, duf,
-                    prettyping, ov, ripgrep, lazygit, lazydocker, trash,
-                    kitty, wezterm, python3
+      Recommended   cargo, starship, uv, direnv, paru, yay, eza, lsd, bat,
+                    btop, dust, duf, prettyping, ov, ripgrep, lazygit,
+                    lazydocker, trash, kitty, wezterm, python3
 
     fish-deps
     fish-deps install
@@ -1347,10 +1347,7 @@ fish-deps manages these tools. Run `fish-deps` to check status, or
 
 ## Required
 
-    cargo     Rust toolchain (via rustup)
     fish      Fish shell >= 4.0
-    fisher    Fish plugin manager
-    starship  Cross-shell prompt
     fzf       Fuzzy finder
     zoxide    Smart cd with frecency
 
@@ -1361,6 +1358,11 @@ fish-deps manages these tools. Run `fish-deps` to check status, or
 
 ## Recommended
 
+    cargo       Rust toolchain (via rustup); used by fish-deps to install
+                Rust-based tools and to build fish from source. All paths
+                are gated on type -q cargo and degrade gracefully.
+    starship    Cross-shell prompt; loaded via type -q starship guard.
+                Without it fish falls back to its built-in default prompt.
     uv          Python package and project manager (Astral); used by the
                 fish-from-source build path in fish-deps. All consumers
                 degrade gracefully without it.

functions/_fish_deps_catalog.fish

@@ -14,27 +14,27 @@
 #   echo $_fdc_bins
 function _fish_deps_catalog
     set -g _fdc_bins \
-        uv cargo fish fisher starship fzf zoxide direnv paru yay \
+        uv cargo fish starship fzf zoxide direnv paru yay \
         wakatime tailscale \
         eza lsd bat btop dust duf prettyping ov rg lazygit lazydocker trash kitty wezterm python3
 
     set -g _fdc_tiers \
-        rec req req req req req req rec rec rec \
+        rec rec req rec req req rec rec rec \
         int int \
         rec rec rec rec rec rec rec rec rec rec rec rec rec rec rec
 
     set -g _fdc_cargo \
-        "" "" "" "" starship "" zoxide "" "" "" \
+        "" "" "" starship "" zoxide "" "" "" \
         "" "" \
         eza lsd bat "" du-dust "" "" ov ripgrep "" "" trashy "" "" ""
 
     set -g _fdc_pm \
-        uv cargo fish "" starship fzf zoxide direnv "" yay \
+        uv cargo fish starship fzf zoxide direnv "" yay \
         wakatime tailscale \
         eza lsd bat btop dust duf prettyping ov ripgrep lazygit lazydocker trash kitty wezterm python
 
     set -g _fdc_special \
-        curl-uv rustup-installer git-cargo-fish fisher-bootstrap curl-installer fzf-update "" "" paru-build yay-build \
+        curl-uv rustup-installer git-cargo-fish curl-installer fzf-update "" "" paru-build yay-build \
         wakatime-binary "" \
         "" "" "" "" "" "" "" "" "" "" curl-lazydocker "" "" "" ""
 end

functions/_fish_deps_install.fish

@@ -92,9 +92,6 @@ function _fish_deps_install
                 case fzf-update
                     set -a methods special-fzf
                     set -a method_labels "git clone (~/.fzf)"
-                case fisher-bootstrap
-                    set -a methods special-fisher
-                    set -a method_labels "curl bootstrap (fisher)"
                 case curl-installer
                     set -a methods special-curl
                     set -a method_labels "curl installer"
@@ -202,9 +199,6 @@ function _fish_deps_install
                     rm -rf "$_tmpdir"
                 case special-fzf
                     fzf-update
-                case special-fisher
-                    curl -sL https://raw.githubusercontent.com/jorgebucaran/fisher/main/functions/fisher.fish | source
-                    fisher update
                 case special-curl
                     if test "$bin" = starship
                         curl -sS https://starship.rs/install.sh | sh