fix(deps): remove paru install, enforce cargo preference for Rust tools

Catalog: clear paru's pm and special install entries so it appears in
status but fish-deps install skips it (it's a package manager, not a
managed dep).

Install: cargo is now always attempted first for Rust tools. When cargo
is absent but a crate exists, a note is printed suggesting rustup.
When only one method is available the chosen method is shown so the user
can see whether cargo or the system PM is being used. Method prompt now
shows the default label inline for clarity.

Removed dead paru-build switch case from the install executor.

functions/_fish_deps_catalog.fish

@@ -10,7 +10,7 @@
 #   _fdc_cargo   — cargo crate name, or "" if not on crates.io
 #   _fdc_pm      — system PM package name, or "" if not in repos
 #   _fdc_special — special install key: fisher-bootstrap | fzf-update |
-#                  paru-build | pipx | curl-installer | "" (none)
+#                  pipx | curl-installer | "" (none)
 function _fish_deps_catalog
     set -g _fdc_bins \
         fish fisher starship fzf zoxide direnv paru \
@@ -28,12 +28,12 @@ function _fish_deps_catalog
         eza lsd bat "" du-dust "" "" "" ripgrep "" "" trash-cli "" ""
 
     set -g _fdc_pm \
-        fish "" starship fzf zoxide direnv paru \
+        fish "" starship fzf zoxide direnv "" \
         wakatime tailscale \
         eza lsd bat btop dust duf prettyping most ripgrep lazygit lazydocker trash kitty wezterm
 
     set -g _fdc_special \
-        "" fisher-bootstrap curl-installer fzf-update "" "" paru-build \
+        "" fisher-bootstrap curl-installer fzf-update "" "" "" \
         pipx "" \
         "" "" "" "" "" "" "" "" "" "" "" "" "" ""
 end