refactor: full DDD + Clean Architecture refactor

- Hapus src/utils/ (17 files) + src/db/ (8 files) dead code
- Absorb 7 re-export stubs → real impl di lokasi DDD
- Buat src/infrastructure/di.ts (DI container)
- Rewrite 5 controllers pakai repository/DI
- Fix shared/utils imports, env.ts, routes, index.ts
- Update package.json build path migrate
- Lint clean, build clean

src/index.ts

@@ -12,7 +12,7 @@ import { metricsCollector } from './shared/metrics/index';
 
 // ─── Auto-run migration at startup ──────────────────────────────────────────
 try {
-  const { runMigration } = await import('./db/migrate');
+  const { runMigration } = await import('./infrastructure/persistence/drizzle/migrate');
   await runMigration();
 } catch {
   logger.warn('Auto-migration skipped (non-fatal)');