fix: reduce db pool size to prevent connection exhaustion, sort grouped views by count

Pool was 20+10 overflow per engine; uvicorn --reload leaked pools until
Postgres hit max_connections=100. Reduced to 5+5 with pool_pre_ping.

Grouped views (tags, people, colors, rated) now sort cards largest-first.

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

frontend/src/components/rated/RatedView.tsx

@@ -37,7 +37,7 @@ export function RatedView() {
       }
     }
 
-    // Highest rating first
+    // Sort by count, biggest first
     const result: RatingGroup[] = []
     for (let r = 5; r >= 1; r--) {
       const photos = buckets.get(r) ?? []
@@ -49,6 +49,7 @@ export function RatedView() {
         representative: photos[0],
       })
     }
+    result.sort((a, b) => b.count - a.count)
     return result
   }, [allPhotos])