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/components/game/tabs/PrestigeTab.test.ts

@@ -28,9 +28,9 @@ describe('Tab barrel export', () => {
 // ─── Test: Prestige upgrade definitions ────────────────────────────────────────
 
 describe('Prestige upgrade definitions', () => {
-  it('has exactly 14 prestige upgrades', async () => {
+  it('has exactly 13 prestige upgrades', async () => {
     const { PRESTIGE_DEF } = await import('@/lib/game/constants/prestige');
-    expect(Object.keys(PRESTIGE_DEF).length).toBe(14);
+    expect(Object.keys(PRESTIGE_DEF).length).toBe(13);
   });
 
   it('all upgrades have required fields', async () => {
@@ -46,7 +46,7 @@ describe('Prestige upgrade definitions', () => {
   it('all 14 expected upgrade IDs are present', async () => {
     const { PRESTIGE_DEF } = await import('@/lib/game/constants/prestige');
     const expectedIds = [
-      'manaWell', 'manaFlow', 'deepMemory', 'insightAmp', 'spireKey',
+      'manaWell', 'manaFlow', 'insightAmp', 'spireKey',
       'temporalEcho', 'steadyHand', 'ancientKnowledge', 'elementalAttune',
       'spellMemory', 'guardianPact', 'quickStart', 'elemStart',
       'unlockedManaTypeCapacity',