refactor: remove memory slot system and Memories section from PrestigeTab

- Remove deepMemory prestige upgrade from constants/prestige.ts
- Remove Memory interface from types.ts
- Remove memorySlots, memories, addMemory, removeMemory, clearMemories from prestigeStore.ts
- Remove deepMemory/memory references from gameLoopActions.ts
- Remove MemoriesCard component and its usage from PrestigeTab.tsx
- Remove memorySlots display from LoopStatsSection.tsx
- Update tests: store-actions-combat-prestige.test.ts, PrestigeTab.test.ts, tick-integration.test.ts

The memory slot system was fully wired but had no gameplay mechanic — addMemory()
was never called outside tests. This removes dead code across 9 files.

src/lib/game/stores/gameLoopActions.ts

@@ -39,8 +39,6 @@ export const createStartNewLoop = (set: (state: Partial<GameCoordinatorState>) =
   usePrestigeStore.getState().resetPrestigeForNewLoop(
     total,
     pu,
-    prestigeState.memories,
-    3 + (pu.deepMemory || 0)
   );
   usePrestigeStore.getState().incrementLoopCount();