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.