fix: use millisecond timestamp in save mock for correct stale comparison

resolveDialogStateFromStatus compares workflow.lastModified (stored
as-is from the mock) with publishedAt.getTime() (milliseconds).
Date.now() / 1000 returned seconds, making lastModified always less
than publishedAtMs, so the dialog never showed 'stale' state.

browser_tests/tests/dialogs/shareWorkflowDialog.spec.ts

@@ -132,7 +132,7 @@ async function saveAndWait(
           body: JSON.stringify({
             path: `workflows/${filename}`,
             size: 1024,
-            modified: Date.now() / 1000
+            modified: Date.now()
           })
         })
       } else {