feat(api-v3): implement permissive updates, automatic ID resolution, and structured error reporting

- Added 'x-ae-ignore-extra-fields' header to support stripping unknown fields in POST/PATCH.
- Added automatic resolution of '*_id_random' strings to integer IDs in 'sanitize_payload'.
- Refactored 'post_obj' to return structured (field -> message) validation errors in 'meta.details'.
- Updated 'mk_resp' to support non-string 'details' in response metadata.
- Added 'tests/verify_feedback_fixes.py' to validate logic changes.

Ref: V3 API Refinement Feedback from mcp_agent.

app/models/response_models.py

@@ -41,7 +41,7 @@ def mk_resp(
         status_message: str = '',
         status_name: str = '',
         success: bool = True,
-        details: str = '',
+        details: Union[None, str, dict, list] = '',
         include: dict = None,
         exclude: dict = None,
         by_alias: bool = True,