feat: robust SSH with fallback menu + comprehensive tests

- Add fallback Rich-based menu when Textual fails
- Working chess game via simple terminal UI
- Proper PTY/terminal handling for SSH
- Added pytest test suite:
  - SSH auth tests (no-auth, accept any)
  - Mode selection tests (play/learn/watch)
  - Chess board widget tests
  - Move validation tests
  - Game state detection tests
- CI workflow for GitHub Actions
- Run tests with: pytest tests/ -v

pyproject.toml

@@ -44,3 +44,10 @@ select = ["E", "F", "I", "N", "W", "UP"]
 [tool.mypy]
 python_version = "3.12"
 strict = true
+
+[tool.pytest.ini_options]
+asyncio_mode = "auto"
+testpaths = ["tests"]
+filterwarnings = [
+    "ignore::DeprecationWarning",
+]