Fix SSL handshake in Google OAuth callback: use httpx native certificate handling instead of custom SSL context

backend/main.py

@@ -17,7 +17,6 @@ import shutil
 from pathlib import Path
 from dotenv import load_dotenv
 import httpx
-import ssl
 import certifi
 from urllib.parse import urlencode, quote
 from datetime import timezone, timedelta
@@ -1134,8 +1133,7 @@ async def google_callback(
         raise HTTPException(status_code=500, detail="Google OAuth credentials not configured")
     
     try:
-        ssl_ctx = ssl.create_default_context(cafile=certifi.where())
-        async with httpx.AsyncClient(verify=ssl_ctx) as client_http:
+        async with httpx.AsyncClient(verify=certifi.where()) as client_http:
             # Exchange authorization code for access token
             token_url = "https://oauth2.googleapis.com/token"