Complete spec: Code alignment and documentation cleanup

- Ensure code aligns with CentralDB models
- Document code alignment with CentralDB models
- Remove informal reference documents (data-model.md, DB_API_SPEC.json, GARMINSYNC_SPEC.md)
- Run linters and formatters (black, isort, mypy)
- Update project configuration files
- Add .dockerignore for Docker builds
- Perform code formatting and import sorting
- Fix type checking issues
- Update documentation files
- Complete implementation tasks as per spec

backend/pyproject.toml

@@ -37,5 +37,5 @@ skip-magic-trailing-comma = false
 line-ending = "auto"
 
 [tool.pytest.ini_options]
-pythonpath = ["src"]
+pythonpath = [".", "src"]
 asyncio_mode = "auto"