Remove detached delivery from review/start (#57667)

## What changed

`review/start` now supports only inline reviews on the supplied thread and returns that thread's id as `reviewThreadId`. Clients can omit `delivery`, send `null`, or specify `"inline"`; `"detached"` is no longer supported.

For a separate review thread, call `thread/start` followed by `review/start`. To preserve conversation history with custom review instructions, use `thread/fork` followed by `turn/start`.

Remove detached review execution and its app-server dependency on `codex-agent-extension`, and update the protocol schemas and generated clients. Preserve `ReviewDelivery.inline` as a Python enum member.

## Testing

Add a Python regression test verifying that inline review delivery parses as `ReviewDelivery.inline` and round-trips to the original JSON.

GitOrigin-RevId: ed16c5271c3315ae3afcb3ee78883ed421394b4d

sdk/python/scripts/update_sdk_artifacts.py

@@ -547,6 +547,9 @@ def _normalized_schema_bundle_text(schema_dir: Path) -> str:
                 required.remove(field)
         for name, definition in definitions.items():
             if isinstance(definition, dict):
+                if name == "ReviewDelivery":
+                    # Preserve ReviewDelivery.inline when only one delivery mode remains.
+                    definition["x-enum-field-as-literal"] = False
                 if name == "CodexErrorInfo":
                     _normalize_open_ended_enum(definition)
                 _flatten_string_enum_one_of(definition)