feat: add Python app auto-deploy flow

[GeorgePearse]

Summary

• make the Python backend the deployable system entrypoint and serve the bundled frontend from FastAPI
• build the frontend into the production Docker image and add a production compose file for the full app stack
• add a GitHub Actions workflow that publishes the app image to GHCR and can optionally deploy it over SSH
• document the backend maturity decision and production rollout requirements

Why Python, not Rust

The Python backend is the only backend that already owns the integrated system surface today: WebUI API, frontend compatibility endpoints, ClickHouse runtime wiring, and the existing Docker path. The Rust backend compiles and tests, but it is still a runner backend rather than the deployable application boundary.

Testing

• cargo test --manifest-path genesis_rust_backend/Cargo.toml
• python3 -m compileall genesis/webui/backend_server.py
• frontend production build not fully verified in this pass because npm install/build stalled on local package install state