feat(deps): add fish-deps unified dependency management command

Introduces `fish-deps` with four subcommands:
- status: colored installed/missing report per tier (required/integrations/recommended)
- install: interactively install each missing dep, prompts method when multiple exist
- update: update all installed deps using their preferred method
- sync: install missing then update installed

Install method priority: cargo (Rust tools get latest crate) > system PM
(paru/pacman/apt/brew/pkg/dnf/yum) > git clone (fzf via fzf-update) >
curl installer (starship, fisher) > pipx (wakatime).

Splits into focused helper files:
- _fish_deps_catalog.fish: parallel-array dep catalog with tiers, cargo crates, PM names, special install keys
- _fish_deps_pm.fish: PM detection and install/upgrade helpers
- _fish_deps_status.fish: tier-grouped colored status display
- _fish_deps_install.fish: per-dep interactive install with method selection
- _fish_deps_update.fish: per-dep update using known install method

check_fish_deps becomes a thin wrapper delegating to `fish-deps status`.
README updated with Dependency Management section.

functions/_fish_deps_status.fish

@@ -0,0 +1,35 @@
+# Copyright (C) 2026 Rootiest
+# SPDX-License-Identifier: AGPL-3.0-or-later
+
+# Print colored installed/missing status for all deps, grouped by tier.
+function _fish_deps_status
+    _fish_deps_catalog
+
+    function __fds_print_dep --argument-names bin
+        if type -q $bin
+            set_color green; echo -n "   "; set_color normal
+            echo -n "$bin "
+            set_color brblack; echo "(Found at "(type -p $bin)")"; set_color normal
+        else
+            set_color red; echo -n "   "; set_color normal
+            echo -n "$bin "
+            set_color brblack; echo "(Not installed)"; set_color normal
+        end
+    end
+
+    for tier_label in "Required Dependencies:req" "Integrations:int" "Recommended Dependencies:rec"
+        set -l label (string split : $tier_label)[1]
+        set -l tier  (string split : $tier_label)[2]
+        set_color cyan; echo $label; set_color normal
+        set -l i 1
+        for bin in $_fdc_bins
+            if test "$_fdc_tiers[$i]" = $tier
+                __fds_print_dep $bin
+            end
+            set i (math $i + 1)
+        end
+        echo ""
+    end
+
+    functions -e __fds_print_dep
+end