Add interactive graph editor connections: port-based edges, drag-connect, and detach

- Add visible typed ports on graph nodes (colored dots for each edge type)
- Route edges to specific port positions instead of node center
- Drag from output port to compatible input port to create/change connections
- Right-click edge context menu with Disconnect option
- Delete key detaches selected edge
- Mark nested edges (composite layers, zones) as non-editable with dotted style
- Add resolve_ref helper for empty-string sentinel to clear reference fields
- Apply resolve_ref across all storage stores for consistent detach support
- Add connection mapping module (graph-connections.js) with API field resolution
- Add i18n keys for connection operations (en/ru/zh)

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

server/src/wled_controller/storage/automation_store.py

@@ -84,11 +84,11 @@ class AutomationStore(BaseJsonStore[Automation]):
         if conditions is not None:
             automation.conditions = conditions
         if scene_preset_id != "__unset__":
-            automation.scene_preset_id = scene_preset_id
+            automation.scene_preset_id = None if scene_preset_id == "" else scene_preset_id
         if deactivation_mode is not None:
             automation.deactivation_mode = deactivation_mode
         if deactivation_scene_preset_id != "__unset__":
-            automation.deactivation_scene_preset_id = deactivation_scene_preset_id
+            automation.deactivation_scene_preset_id = None if deactivation_scene_preset_id == "" else deactivation_scene_preset_id
         if tags is not None:
             automation.tags = tags