Stop the capture script seeding a node into a populated flow

Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01H7LwYgJfpkbLCTeiAf8U4A

frontend/scripts/capture-screenshots.mjs

@@ -117,6 +117,13 @@ async function captureFlows(page, dir) {
     await page.getByTestId("create-flow").click()
   }
   await page.waitForURL(/\/flows\/.+/, { timeout: 15000 })
+  // The canvas paints before the flow detail arrives, so counting nodes right
+  // away reads 0 for a populated flow — and the seeding below would then add a
+  // node to somebody's real flow. Wait until it says which of the two it is.
+  await page
+    .locator(".react-flow__node, [data-testid=flow-empty]")
+    .first()
+    .waitFor({ timeout: 15000 })
 
   if (!(await page.locator(".react-flow__node").count())) {
     await page.getByTestId("add-node").click()