Write project.json to the storage owner prefix.

update_project used meta.user_id for the path, so JWT projects that still
have user_id=local never persisted pcb_status=queued and the PCB worker
exited as draft. Point writes at the prefix used to read the project.

frontend/src/app/(app)/project/[id]/pcb/page.tsx

@@ -28,6 +28,7 @@ export default function PcbReviewPage({
   const { id } = use(params);
   const [projectName, setProjectName] = useState("");
   const [pcbStatus, setPcbStatus] = useState<string>("draft");
+  const [analysisBusy, setAnalysisBusy] = useState(false);
   const [inventory, setInventory] = useState<{
     nets: Array<Record<string, unknown>>;
     domains: string[];
@@ -49,6 +50,7 @@ export default function PcbReviewPage({
       .then((p) => {
         setProjectName(p.name);
         setPcbStatus(p.pcbStatus ?? "draft");
+        setAnalysisBusy(p.status === "running" || p.status === "queued");
         setStatusLoaded(true);
       })
       .catch(() => setStatusLoaded(true));
@@ -198,8 +200,19 @@ export default function PcbReviewPage({
         </Card>
       )}
 
+      {statusLoaded && pcbStatus === "draft" && analysisBusy && (
+        <p className="text-sm text-muted-foreground">
+          Schematic review is still running. Wait for it to finish (or cancel
+          it), then start PCB review — the two jobs cannot run at the same time.
+        </p>
+      )}
+
       {statusLoaded && pcbStatus === "draft" && (
-        <Button size="sm" disabled={starting} onClick={handleStart}>
+        <Button
+          size="sm"
+          disabled={starting || analysisBusy}
+          onClick={handleStart}
+        >
           <CircuitBoard className="h-4 w-4 mr-1" />
           {starting ? "Starting…" : "Run PCB review"}
         </Button>