feat: maximize minimized groups on double-click

Add double-click handler for minimized groups to quickly maximize them,
providing a faster alternative to using the context menu.

Implementation:
- Add handleNodeDoubleClick callback in GraphEditor
- Check if double-clicked node is a minimized group
- Call toggleGroupMinimized to maximize the group
- Wire handler to ReactFlow's onNodeDoubleClick prop

This improves UX by allowing users to quickly expand minimized groups
to see and edit individual relations within them.

🤖 Generated with [Claude Code](https://claude.com/claude-code)

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

src/components/Editor/GraphEditor.tsx

@@ -822,6 +822,21 @@ const GraphEditor = ({ onNodeSelect, onEdgeSelect, onGroupSelect, onMultiSelect,
     setContextMenu(null); // Close context menu if open
   }, []);
 
+  // Handle node double-click - maximize minimized groups
+  const handleNodeDoubleClick = useCallback(
+    (_event: React.MouseEvent, node: Node) => {
+      // Check if this is a minimized group
+      if (node.type === 'group') {
+        const groupData = node.data as Group['data'];
+        if (groupData.minimized) {
+          // Toggle to maximize the group
+          toggleGroupMinimized(node.id);
+        }
+      }
+    },
+    [toggleGroupMinimized],
+  );
+
   // Handle edge click - ReactFlow handles selection automatically
   const handleEdgeClick = useCallback(() => {
     setContextMenu(null); // Close context menu if open
@@ -1058,6 +1073,7 @@ const GraphEditor = ({ onNodeSelect, onEdgeSelect, onGroupSelect, onMultiSelect,
         onNodesDelete={handleNodesDelete}
         onEdgesDelete={handleEdgesDelete}
         onNodeClick={handleNodeClick}
+        onNodeDoubleClick={handleNodeDoubleClick}
         onEdgeClick={handleEdgeClick}
         onNodeContextMenu={handleNodeContextMenu}
         onEdgeContextMenu={handleEdgeContextMenu}