[Jemade]

Optional webhook dispatch failures previously entered the generation failure handler after a successful audit, risking a duplicate primary key and replacing a successful response. Restrict the provider exception handler to generation, isolate webhook failures, and roll back failed notification transactions. Preserve successful generation responses and original provider exceptions.

Fix setuptools package discovery for editable installs and declare SQLAlchemy's asyncio extra. Update README behavior and add regression tests for successful and failed generation with webhook errors.

Validation: editable install succeeds; 44 tests passed; Ruff lint and full format check passed; mypy passed (40 source files). Tests use SQLite and mocked upstream services. No deployment performed.