fix(phase-0): resolve import paths and add backward compatibility test

- Fix TypeScript import paths to use relative imports instead of aliases
- Add comprehensive backward compatibility test script
- Verify existing functionality works correctly:
  * Legacy /api/track endpoint: ✅
  * /api/v1/track POST endpoint: ✅
  * /api/v1/track GET endpoint: ✅
- Ready for Docker testing of new TypeScript implementation

apps/api/src/index.ts

@@ -13,8 +13,8 @@ import compression from 'compression';
 import cookieParser from 'cookie-parser';
 import rateLimit from 'express-rate-limit';
 import path from 'path';
-import { logger } from '@/lib/logger';
-import { trackRedirects } from '@/services/redirect-legacy.service';
+import { logger } from './lib/logger';
+import { trackRedirects } from './services/redirect-legacy.service';
 
 const app = express();
 const PORT = process.env.PORT || 3333;