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

install-plasmoid.sh

@@ -0,0 +1,12 @@
+#!/bin/bash
+set -e
+
+PLASMOID_DIR="$(dirname "$0")/plasmoid/at.sub-net.elgato"
+
+# Remove old version if installed
+kpackagetool6 -t Plasma/Applet -r at.sub-net.elgato 2>/dev/null || true
+
+# Install
+kpackagetool6 -t Plasma/Applet -i "$PLASMOID_DIR"
+
+echo "Plasmoid installed. Add 'Elgato Key Light' to your panel or system tray."