50750f3183
Replaces per-provider logging.debug body with _list_models_for_provider_result SDK-boundary helper. Aggregates per-provider failures into self._model_fetch_errors and returns Result with aggregated errors. Stderr summary on partial failure. The SDK boundary (ai_client.list_models call) is the canonical place to catch vendor exceptions and convert to ErrorInfo(kind=NETWORK), per error_handling.md §'Boundary Types'. Audit: INTERNAL_SILENT_SWALLOW for src/app_controller.py: 23 -> 22.