add IGDB metadata enrichment, image proxy, rich game UI

server: metadata cache + fetch service, image proxy with disk cache,
POST /igdb/metadata + GET /igdb/image/:id/:size routes.
client: 002-metadata migration, enrichment wired into sync pipeline,
extracted SyncProgress component, square cover icons in list items,
genres/rating/summary on discover cards, tap-to-navigate on card stack,
rich game detail with screenshots, trailer embed, developer info.

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

.gitignore

@@ -15,6 +15,8 @@ node_modules
 
 # IGDB cache (generated at runtime)
 server/data/igdb-cache.json
+server/data/igdb-metadata.json
+server/data/igdb-images/
 
 # Build outputs
 dist