fix(delete): redirect Delete to owning component when target is empty linked node

Linked Craft.js nodes (column children of ColumnLayout, section-inner of
Section, etc.) are structurally non-deletable — actions.delete throws and
the error was silently swallowed. Empty layouts ended up undeletable from
the canvas because clicks always landed on the linked children that fill
the layout's visible area.

Adds findDeletableTarget(): when target is a linked node and ALL its
linked siblings are also empty (i.e., the layout itself is empty),
redirect deletion to the owning parent. Refuses to redirect when any
sibling has content, to protect against nuking a 3-col layout that has
content in other cols.

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

craft/src/panels/context-menu/ContextMenu.tsx

@@ -1,5 +1,6 @@
 import React, { useEffect, useCallback, useRef } from 'react';
 import { useEditor } from '@craftjs/core';
+import { findDeletableTarget } from '../../utils/craft-helpers';
 
 interface ContextMenuProps {
   visible: boolean;
@@ -143,14 +144,18 @@ export const ContextMenu: React.FC<ContextMenuProps> = ({
   }, [nodeId, actions, getParentId, onClose]);
 
   const deleteNode = useCallback(() => {
-    if (!nodeId || nodeId === 'ROOT') return;
+    const target = findDeletableTarget(query, nodeId);
+    if (!target) {
+      onClose();
+      return;
+    }
     try {
-      actions.delete(nodeId);
+      actions.delete(target);
     } catch (e) {
       console.error('Delete failed:', e);
     }
     onClose();
-  }, [nodeId, actions, onClose]);
+  }, [nodeId, actions, query, onClose]);
 
   if (!visible) return null;