test: use page.route() to serve local fixture for URI drop test

Replace external GitHub Pages URL with page.route() interception
to make the Vue node URI drop test hermetic and avoid flakiness
from network dependencies.

browser_tests/tests/loadWorkflowInMedia.spec.ts

@@ -71,6 +71,13 @@ test.describe(
     test('Load workflow from URL dropped onto Vue node', async ({
       comfyPage
     }) => {
+      const fakeUrl = 'https://example.com/workflow.png'
+      await comfyPage.page.route(fakeUrl, (route) =>
+        route.fulfill({
+          path: comfyPage.assetPath('workflowInMedia/workflow_itxt.png')
+        })
+      )
+
       await comfyPage.settings.setSetting('Comfy.VueNodes.Enabled', true)
       await comfyPage.vueNodes.waitForNodes()
 
@@ -85,10 +92,10 @@ test.describe(
         y: box!.y + box!.height / 2
       }
 
-      await comfyPage.dragDrop.dragAndDropURL(
-        'https://comfyanonymous.github.io/ComfyUI_examples/hidream/hidream_dev_example.png',
-        { dropPosition, preserveNativePropagation: true }
-      )
+      await comfyPage.dragDrop.dragAndDropURL(fakeUrl, {
+        dropPosition,
+        preserveNativePropagation: true
+      })
 
       await comfyPage.page.waitForFunction(
         (prevCount) => window.app!.graph.nodes.length !== prevCount,