fix: remove UploadBatcher crash window, make bot concurrency configurable, fix all test import paths

- Removed UploadBatcher (src/infrastructure/telegram/upload-batcher.ts + DI):
  pending uploads no longer lost on crash, files sent directly to Telegram
- Changed upload-controller to use Bun.file().stream() instead of createReadStream
- Made PER_BOT_CONCURRENCY configurable via TELEGRAM_BOT_CONCURRENCY env
- Fixed 18 test files with updated import paths and mock shapes
- Updated package.json test script: telegramQueue.test.ts → bot-pool.test.ts
- Build, lint, and test suite all pass

test/auth.test.ts

@@ -17,7 +17,7 @@ setEnv('ADMIN_API_TOKEN', 'route-secret-token');
 setEnv('SESSION_COOKIE_NAME', 'route_session');
 setEnv('SESSION_COOKIE_MAX_AGE_SECONDS', '3600');
 
-const auth = await import('../src/utils/auth');
+const auth = await import('../src/interfaces/http/middleware/auth');
 
 describe('auth utilities', () => {
   const secret = 'admin-secret-token';