Fix: Enforce Python 3.11.9 and use pinned wheels for fast build

backend/requirements.txt

@@ -1,14 +1,14 @@
-fastapi>=0.110.0
-uvicorn>=0.29.0
-python-dotenv>=1.0.1
-pydantic>=2.8.0
-requests>=2.31.0
-python-multipart>=0.0.9
+fastapi==0.110.0
+uvicorn==0.29.0
+python-dotenv==1.0.1
+pydantic==2.7.0
+requests==2.31.0
+python-multipart==0.0.9
 # AI / LangGraph
-langgraph>=0.1.0
-langchain-core>=0.2.0
-langchain-openai>=0.1.0
+langgraph==0.0.30
+langchain-core==0.1.40
+langchain-openai==0.1.1
 # Media Services
-assemblyai>=0.26.0
-elevenlabs>=1.0.0
-google-generativeai>=0.5.0
+assemblyai==0.26.0
+elevenlabs==1.0.0
+google-generativeai==0.5.0

render.yaml

@@ -6,7 +6,7 @@ services:
     startCommand: cd backend && bash start.sh
     envVars:
       - key: PYTHON_VERSION
-        value: 3.11.0
+        value: 3.11.9
       - key: OPENROUTER_API_KEY
         fromGroup: talenttalk-secrets
       - key: GOOGLE_API_KEY