feat(deps): add Optional/Terminal Emulator tiers, fix docker prompt hang and ov install path

Reworks fish-deps' dependency classification from three tiers to five:
Required, Recommended, Optional, Terminal Emulators, and Integrations.

- Add an Optional tier for single-purpose wrapper conveniences that only
  matter if you already use that specific tool (btop, dust, duf,
  prettyping, go, lazygit, lazydocker, docker, yt-dlp, screen). Skipped by
  `fish-deps install`/`sync` by default.
- Split kitty/wezterm into their own Terminal Emulators tier, since only
  the one matching $TERM is ever relevant to a given user.
- Add --optional, --terminals, and --all flags to `install`/`sync` to
  opt back into the skipped tiers, with a summary of how many were
  skipped and which flag restores them.
- Fix `_fish_deps_status` marking missing Integrations as critical (red)
  the same as Required — only Required is red now; Recommended stays
  yellow, everything else renders as a neutral dim note.

Also fixes two bugs surfaced during dependency testing on a fresh
install:

- `fish_right_prompt` called `docker context show` on every prompt with
  no `type -q docker` guard, unlike every other optional integration in
  this config — on a system without docker this printed a visible
  "Unknown command: docker" block on every single prompt render. Added
  the missing guard, and hardened the `ld` wrapper with explicit
  docker/lazydocker presence checks.
- `ov`'s catalog entry offered `cargo install ov` as its preferred
  install method, but crates.io's `ov` is an unrelated crate, not the
  noborus/ov pager — cargo would silently install the wrong package.
  Removed the cargo path; `ov` now prefers `go install
  github.com/noborus/ov@latest` (ahead of the system PM) when go is
  available, since not all distros package `ov` in their base repos,
  and falls back to the system PM otherwise.

functions/_fish_deps_update.fish

@@ -72,6 +72,21 @@ function _fish_deps_update
             continue
         end
 
+        # ov: prefer go install (always fetches latest); fall back to system PM
+        if test "$special" = go-ov
+            if type -q go
+                echo "Updating $bin..."
+                go install github.com/noborus/ov@latest
+                set updated_any 1
+            else if test -n "$pm_pkg"; and test -n "$pm"
+                echo "Updating $bin (go unavailable, using system PM)..."
+                _fish_deps_pm_upgrade $pm_pkg
+                set updated_any 1
+            end
+            set i (math $i + 1)
+            continue
+        end
+
         # lazydocker: re-run the official install/update script
         if test "$special" = curl-lazydocker
             echo "Updating $bin..."