Docs: second improvement pass

- tutorial-auth: fix deprecated datetime.utcnow() → datetime.now(timezone.utc),
  add role-based access control section, add auth strategy comparison
- tutorial-websockets: use WebSocketDisconnect instead of bare Exception,
  add connection lifecycle section, add rejected connection test example
- tutorial-sqlalchemy: modernize to mapped_column() / Mapped[] (SQLAlchemy 2.0)
- deployment: use uv in Docker example, fix stale uv.lock reference
- quickstart: link to all tutorials in "next steps"
- sandbox: rewrite with project layout, mypy, and pattern-matching test examples

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

docs/source/quickstart.rst

@@ -376,3 +376,9 @@ jump into the tutorials:
 - :doc:`tutorial-rest` — build a full CRUD API with validation
 - :doc:`tutorial-sqlalchemy` — connect to a database
 - :doc:`tutorial-auth` — add authentication
+- :doc:`tutorial-websockets` — real-time communication
+- :doc:`tutorial-middleware` — hooks and middleware
+- :doc:`tutorial-flask` — migrating from Flask
+- :doc:`guide-config` — environment variables and secrets
+- :doc:`deployment` — Docker, cloud platforms, and production
+- :doc:`testing` — writing tests with pytest