fix: compatibility with multi-design schema for scan/zigbee/liveview/CustomStyleModal

- liveview.py: replace hardcoded CanvasState PK lookup (get(1)) with
  design_id-aware query; filter nodes/edges by design_id
- scan.py: add design_id to bulk approve, single approve, and edge
  resolution Node/Edge constructors (fallback to first design)
- zigbee.py: add design_id to coordinator auto-approval Node constructor
- schemas/nodes.py: add design_id to NodeCreate and NodeResponse
- schemas/edges.py: add design_id to EdgeCreate
- CustomStyleModal.tsx: add 'electrical' to EDITABLE_EDGE_TYPES

backend/app/schemas/nodes.py

@@ -34,7 +34,7 @@ class NodeBase(BaseModel):
 
 
 class NodeCreate(NodeBase):
-    pass
+    design_id: str | None = None
 
 
 class NodeUpdate(BaseModel):
@@ -68,6 +68,8 @@ class NodeUpdate(BaseModel):
 
 class NodeResponse(NodeBase):
     id: str
+    design_id: str | None = None
+    ieee_address: str | None = None
     last_seen: datetime | None = None
     response_time_ms: int | None = None
     created_at: datetime