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/wled_output_target.py

@@ -5,6 +5,7 @@ from datetime import datetime, timezone
 from typing import List, Optional
 
 from wled_controller.storage.output_target import OutputTarget
+from wled_controller.storage.utils import resolve_ref
 
 DEFAULT_STATE_CHECK_INTERVAL = 30  # seconds
 
@@ -68,11 +69,11 @@ class WledOutputTarget(OutputTarget):
         """Apply mutable field updates for WLED targets."""
         super().update_fields(name=name, description=description, tags=tags)
         if device_id is not None:
-            self.device_id = device_id
+            self.device_id = resolve_ref(device_id, self.device_id)
         if color_strip_source_id is not None:
-            self.color_strip_source_id = color_strip_source_id
+            self.color_strip_source_id = resolve_ref(color_strip_source_id, self.color_strip_source_id)
         if brightness_value_source_id is not None:
-            self.brightness_value_source_id = brightness_value_source_id
+            self.brightness_value_source_id = resolve_ref(brightness_value_source_id, self.brightness_value_source_id)
         if fps is not None:
             self.fps = fps
         if keepalive_interval is not None: