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)

src/app/page.tsx

@@ -44,6 +44,7 @@ import { LeftPanel } from './components/LeftPanel';
 const DisciplinesTab = lazy(() => import('@/components/game/tabs').then(module => ({ default: module.DisciplinesTab })));
 const SpellsTab = lazy(() => import('@/components/game/tabs').then(module => ({ default: module.SpellsTab })));
 const StatsTab = lazy(() => import('@/components/game/tabs').then(module => ({ default: module.StatsTab })));
+const DebugTab = lazy(() => import('@/components/game/tabs').then(module => ({ default: module.DebugTab })));
 const AchievementsTab = lazy(() => import('@/components/game/tabs').then(module => ({ default: module.AchievementsTab })));
 
 const TabLoadingFallback = () => <div className="p-4 text-center text-gray-400">Loading...</div>;
@@ -234,6 +235,7 @@ export default function ManaLoopGame() {
                   <TabsTrigger value="stats" className="text-xs px-2 py-1">📊 Stats</TabsTrigger>
                   <TabsTrigger value="disciplines" className="text-xs px-2 py-1">📚 Disciplines</TabsTrigger>
                   <TabsTrigger value="grimoire" className="text-xs px-2 py-1">📖 Grimoire</TabsTrigger>
+                  <TabsTrigger value="debug" className="text-xs px-2 py-1">🐛 Debug</TabsTrigger>
                   <TabsTrigger value="achievements" className="text-xs px-2 py-1">🏆 Achievements</TabsTrigger>
                 </TabsList>
 
@@ -265,6 +267,14 @@ export default function ManaLoopGame() {
                   <GrimoireTab />
                 </TabsContent>
 
+                <TabsContent value="debug">
+                  <ErrorBoundary fallback={<div className="p-4 text-red-400">debug tab failed to load.</div>}>
+                    <Suspense fallback={<TabLoadingFallback />}>
+                      <DebugTab />
+                    </Suspense>
+                  </ErrorBoundary>
+                </TabsContent>
+
                 <TabsContent value="achievements">
                   <ErrorBoundary fallback={<div className="p-4 text-red-400">achievements tab failed to load.</div>}>
                     <Suspense fallback={<TabLoadingFallback />}>