Summary

• add docs/CONTRIBUTING.md and align local setup docs around uv, project-local caches, and health-check smoke tests
• add an optional backend amap_service for AMap Web Service POI lookup with TTL caching and stub fallback
• wire candidate POI flows through the new service while preserving the existing no-key stub behavior
• ensure SQLite file database parent directories are created during backend startup

Notes

• AMAP_KEY remains optional. Without it, local development and tests continue to use the existing stub data.
• The AMap client degrades back to stub data on missing keys, request failures, empty responses, or invalid coordinates.
• This keeps the change scoped to contributor setup and the POI service boundary, without requiring a paid service for new contributors.

Validation

• uv run pytest -> 60 passed
• npm test -- --run -> 10 passed
• npm run build -> passed
• FastAPI TestClient /health -> 200 {'status': 'ok'}