Add clone support for scene presets and update TODO

- Add clone_preset() to ScenePresetStore with deep copy of target snapshots
- Add POST /scene-presets/{id}/clone API endpoint
- Add clone button to scene preset cards in Automations tab
- Add i18n keys for clone feedback in all 3 locales
- Add TODO items for dashboard stats collapse and protocol badge review

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

server/src/wled_controller/static/locales/en.json

@@ -681,6 +681,8 @@
   "scenes.error.activate_failed": "Failed to activate scene",
   "scenes.error.recapture_failed": "Failed to recapture scene",
   "scenes.error.delete_failed": "Failed to delete scene",
+  "scenes.cloned": "Scene cloned",
+  "scenes.error.clone_failed": "Failed to clone scene",
   "time.hours_minutes": "{h}h {m}m",
   "time.minutes_seconds": "{m}m {s}s",
   "time.seconds": "{s}s",