refactor: remove Python monitoring components

Remove the Python Flask backend and reporter, keeping only the TypeScript
implementations. The JSON schemas in reporter/schemas/ are retained as
they define the report format contract used by CLI tests.

Removed:
- monitoring_flask_backend/ (Python Flask backend)
- reporter/*.py (Python reporter code)
- reporter/Dockerfile
- tests/monitoring_flask_backend/ (Python tests)
- tests/reporter/ (Python tests)

Retained:
- reporter/schemas/*.json (JSON schema files for report validation)

Author: claude