docs(catalog): migrate opinionated component catalog into fish-config.md

Promotes the internal opinionated_catalog.md (git-ignored dev reference)
to first-class user documentation in docs/fish-config.md Section 7.

- Add per-category component tables (C1–C6) under a new "Component
  Reference" subsection in "Opinionated Components (Minimal Mode)"
- Document the C5 sentinel-file coordination mechanism and how
  __fish_config_logging_changed propagates changes to all open shells
- Document C3/C5 composition (smart_exit wrapper vs capture block)
- Document bang-bang system atomicity across its multiple source files
- Add rg function entry to Section 5.1 (Kitty hyperlink wrapper)
- Update fish-config.index with keywords for all new headings

docs/fish-config.index

@@ -71,6 +71,7 @@ mkdir=### mkdir
 mkcd=### mkcd
 poke=### poke
 rm=### rm
+rg=### rg
 scrub=### scrub
 nav-fns=## 5.2 Navigation
 cdi=### cdi
@@ -167,6 +168,24 @@ minimal=## Opinionated Components (Minimal Mode)
 minimal-mode=## Opinionated Components (Minimal Mode)
 opt-out=## Opinionated Components (Minimal Mode)
 toggles=## Opinionated Components (Minimal Mode)
+component-reference=### Component Reference
+components=### Component Reference
+c1=#### C1 — Command Shadows
+command-shadows=#### C1 — Command Shadows
+aliases-detail=#### C1 — Command Shadows
+c2=#### C2 — Startup Side-Effects
+autoexec=#### C2 — Startup Side-Effects
+startup=#### C2 — Startup Side-Effects
+c3=#### C3 — Key and Environment Overrides
+overrides-detail=#### C3 — Key and Environment Overrides
+bang-bang=#### C3 — Key and Environment Overrides
+c4=#### C4 — Terminal and Tool Integration
+integrations-detail=#### C4 — Terminal and Tool Integration
+c5=#### C5 — Logging and Capture
+logging-detail=#### C5 — Logging and Capture
+logging-sentinel=#### C5 — Logging and Capture
+c6=#### C6 — Greeting and First-Run UI
+greeting=#### C6 — Greeting and First-Run UI
 
 # ── Section 8: Fisher Plugins ─────────────────────────────────
 plugins=# 8. FISHER PLUGINS