fix: sync user name from external auth API and fix audit log schema

- Auth router: Extract user name from nested data.userInfo.name structure
- Auth router: Sync user name on every login (not just on user creation)
- Audit schema: Change changes field type to Optional[Any] to support
  both list and dict formats (fixes 500 error on audit page)

Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>

backend/app/api/auth/router.py

@@ -76,16 +76,26 @@ async def login(
     # Find or create user in local database
     user = db.query(User).filter(User.email == login_request.email).first()
 
+    # Get name from auth API response (nested in data.userInfo.name)
+    user_info = auth_result.get("data", {}).get("userInfo", {})
+    auth_name = user_info.get("name", login_request.email.split("@")[0])
+
     if not user:
         # Create new user based on auth API response
         user = User(
             email=login_request.email,
-            name=auth_result.get("name", login_request.email.split("@")[0]),
+            name=auth_name,
             is_active=True,
         )
         db.add(user)
         db.commit()
         db.refresh(user)
+    else:
+        # Sync user name from external auth system on each login
+        if user.name != auth_name:
+            user.name = auth_name
+            db.commit()
+            db.refresh(user)
 
     if not user.is_active:
         raise HTTPException(