feat: recreate Debug Tab with modular debugging functions

- Add DebugTab.tsx as main container with collapsible sections
- Add 8 debug section components in DebugTab/ subdirectory:
  - GameStateDebugSection: reset, mana, time, pause controls
  - DisciplineDebugSection: activate/deactivate, add XP
  - AttunementDebugSection: unlock, add XP
  - ElementDebugSection: unlock all, add elemental mana
  - GolemDebugSection: enable/disable golems
  - PactDebugSection: force sign/clear pacts
  - SpireDebugSection: jump floors, toggle spire mode
  - AchievementDebugSection: unlock/reset achievements
- Add DebugTab to barrel export (tabs/index.ts)
- Add lazy-loaded Debug tab to page.tsx
- Add DebugTab.test.ts with 45 tests
- All files under 400 lines
- Uses existing debug context (DebugProvider, DebugName)
- Destructive actions require confirmation (double-click pattern)

docs/project-structure.txt

@@ -106,6 +106,8 @@ Mana-Loop/
 │   │   │   │   │   └── StudyStatsSection.tsx
 │   │   │   │   ├── AchievementsTab.tsx
 │   │   │   │   ├── ActivityLog.tsx
+│   │   │   │   ├── DebugTab.test.ts
+│   │   │   │   ├── DebugTab.tsx
 │   │   │   │   ├── DisciplinesTab.tsx
 │   │   │   │   ├── SpellsTab.tsx
 │   │   │   │   ├── StatsTab.tsx