[Docs] Note landing two-pool distinction and PINNED_REEL_POSTERS

Add two bullets under Frontend section: clarify that the landing
carousel and "Roll the Dice" draw from separate pools (reel-posters
cache vs. /api/tmdb/popular), and point to PINNED_REEL_POSTERS for
adding/removing always-included carousel entries.

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

CLAUDE.md

@@ -46,6 +46,8 @@ Tables: `users`, `groups`, `group_members`, `movies`, `landing_reel_posters`
 - Real-time: subscribe on mount, unsubscribe on unmount (one list at a time). Home page counts via polling.
 - Accessibility: `aria-live="polite"` for roll results, filter changes, watched toggles. `prefers-reduced-motion` on both animations.
 - Home roll teaser renders in place — do not router.push() from a home-page roll.
+- Landing has two distinct movie pools: carousel reads `landing_reel_posters` via `/api/tmdb/reel-posters`; "Roll the Dice" hits `/api/tmdb/popular?page=N` (random 1–50, ~1000-movie pool). Don't conflate.
+- `PINNED_REEL_POSTERS` in `src/app/api/tmdb/reel-posters/route.ts` always-include list (deduped by `tmdb_id`); edit there to add/remove pins.
 
 ## Auth