[feat] sync node library when subgraph titles change

When a subgraph node is renamed, the node library sidebar now immediately reflects the updated display name. This ensures consistency between the canvas, breadcrumb navigation, and node library.

Key changes:
- Add updateNodeDefDisplayName method to nodeDefStore with reference preservation
- Update TitleEditor to call nodeDefStore for subgraph title changes
- Organize subgraph browser tests into dedicated folder
- Add comprehensive unit test coverage for nodeDefStore

browser_tests/tests/sidebar/nodeLibrary.spec.ts

@@ -336,4 +336,54 @@ test.describe('Node library sidebar', () => {
     await comfyPage.page.waitForTimeout(1000)
     expect(await tab.getNode('KSampler (Advanced)').count()).toBe(2)
   })
+
+  test('Subgraph node display name updates in library when renamed', async ({
+    comfyPage
+  }) => {
+    // Load a workflow with subgraphs to populate the node library
+    await comfyPage.loadWorkflow('nested-subgraph')
+    await comfyPage.nextFrame()
+
+    const tab = comfyPage.menu.nodeLibraryTab
+
+    // Navigate to subgraph folder in node library
+    await tab.getFolder('subgraph').click()
+    await comfyPage.nextFrame()
+
+    // Get initial subgraph node name in the library
+    const initialSubgraphNodeCount = await tab.getNode('Subgraph Node').count()
+    expect(initialSubgraphNodeCount).toBeGreaterThan(0)
+
+    // Get the subgraph node by ID (node 10 is the subgraph)
+    const subgraphNode = await comfyPage.getNodeRefById('10')
+    const nodePos = await subgraphNode.getPosition()
+    const nodeSize = await subgraphNode.getSize()
+
+    // Double-click on the title area of the subgraph node to edit
+    await comfyPage.canvas.dblclick({
+      position: {
+        x: nodePos.x + nodeSize.width / 2,
+        y: nodePos.y - 10 // Title area is above the node body
+      },
+      delay: 5
+    })
+
+    // Wait for title editor to appear
+    await expect(comfyPage.page.locator('.node-title-editor')).toBeVisible()
+
+    // Clear existing text and type new title
+    await comfyPage.page.keyboard.press('Control+a')
+    const newTitle = 'Renamed Subgraph Node'
+    await comfyPage.page.keyboard.type(newTitle)
+    await comfyPage.page.keyboard.press('Enter')
+
+    // Wait a frame for the update to complete
+    await comfyPage.nextFrame()
+
+    // Verify the node library shows the updated title
+    expect(await tab.getNode(newTitle).count()).toBeGreaterThan(0)
+
+    // Verify the old node name is no longer in the library
+    expect(await tab.getNode('Subgraph Node').count()).toBe(0)
+  })
 })