Initial implementation: CLI + KDE Plasma 6 widget for Elgato Key Light

- Python CLI (click): discover, status, on/off/toggle, brightness, temperature, info
- mDNS discovery via zeroconf for automatic light detection
- Shared config at ~/.config/elgato-cli/config.json
- KDE Plasma 6 plasmoid with system tray icon, power/brightness/temperature controls
- Plasmoid uses XMLHttpRequest directly to light API (no CLI dependency)
- Unit tests for API client with mocked HTTP responses

.gitignore

@@ -0,0 +1,10 @@
+__pycache__/
+*.py[cod]
+*$py.class
+*.egg-info/
+dist/
+build/
+*.egg
+.venv/
+venv/
+.pytest_cache/