fix(preview): add 60-second grace period before zombie killer murders booting dev servers throwing 504s

vibn-frontend/app/api/projects/[projectId]/anatomy/route.ts

@@ -825,8 +825,17 @@ async function loadPreviews(projectId: string): Promise<Preview[]> {
             ping.status === 504 ||
             ping.status === 404
           ) {
+            // GRACE PERIOD: If the server was started less than 60 seconds ago,
+            // Traefik might return a 502/504 simply because the Node process hasn't
+            // finished booting and binding to the port yet. Do not kill it!
+            const ageMs = Date.now() - new Date(r.started_at).getTime();
+            if (ageMs < 60_000) {
+              activePreviews.push(r); // Give it the benefit of the doubt
+              return;
+            }
+
             console.warn(
-              `[anatomy] Preview zombie detected for ${r.preview_url} (HTTP ${ping.status}). Marking stopped.`,
+              `[anatomy] Preview zombie detected for ${r.preview_url} (HTTP ${ping.status}, age ${Math.round(ageMs / 1000)}s). Marking stopped.`,
             );
             await query(
               `UPDATE fs_dev_servers SET state = 'stopped' WHERE id = $1`,