Security Phase 1: Update FastAPI from 0.104.1 to 0.109.1

- Fixes SNYK-PYTHON-FASTAPI-6228055 (ReDoS vulnerability)
- Also updates starlette to 0.35.1 (fixes resource allocation issue)
- anyio already at safe version 4.10.0 (fixes race condition)
- Tested locally: All endpoints working correctly
- This fixes 3 HIGH severity vulnerabilities

requirements.txt

@@ -1,5 +1,5 @@
 # Core dependencies for HuggingFace Spaces deployment
-fastapi==0.104.1
+fastapi==0.109.1
 uvicorn[standard]==0.24.0
 websockets==12.0
 python-multipart==0.0.6