Add FastAPI web/API layer and static site

- queries.py: shared read-only query helpers (feed, brief, category counts)
  returning plain dicts, used by the API and available to the CLI.
- api.py: FastAPI service with Pydantic response models (the companion-app
  contract), CORS, and endpoints for categories, feed, brief, and health;
  mounts a static site at /.
- static/index.html: minimal dependency-free site rendering the daily five
  and topic/flavor category browsing.
- 'goodnews serve' command launches uvicorn (lazy import; core CLI stays
  pure-stdlib). Web deps live behind the optional [web] extra.
- Dockerfile + .dockerignore + build-system metadata so the service installs
  and deploys cleanly, with the DB mounted as a shared volume.
- README: web/API and deployment docs.

Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>

.dockerignore

@@ -0,0 +1,7 @@
+.git
+.venv
+data
+__pycache__
+*.pyc
+*.sqlite3
+*.sqlite3-*