Fix Task6: Remove duplicate SpireTab.tsx and verify swarm mode

- Deleted old src/components/game/SpireTab.tsx (duplicate of tabs/SpireTab.tsx)
- Verified SWARM_CONFIG: 15% chance, 3-6 enemies at 40% HP
- Verified UI in tabs/SpireTab.tsx correctly renders each swarm enemy individually
- Verified generateSwarmEnemies() and generateRoomType() logic is correct

src/lib/game/store.ts

@@ -847,8 +847,8 @@ function addActivityLogEntry(
   details?: ActivityLogEntry['details']
 ): ActivityLogEntry[] {
   const entry = createActivityEntry(eventType, message, details);
-  // Keep last 100 entries, newest first
-  return [entry, ...state.activityLog.slice(0, 99)];
+  // Keep last 50 entries, newest first (Task 10)
+  return [entry, ...state.activityLog.slice(0, 49)];
 }
 
 // ─── Game Store ───────────────────────────────────────────────────────────────