fix(api): stop POST /api/keys hanging on the fire-and-forget Cloud sync (#6570) (#6624)

cloudEnabled defaults to true in settings.ts::getSettings() for any install
with no persisted settings row (every fresh install), so the create-key
handler's unconditional `await syncKeysToCloudIfEnabled()` always attempted a
real outbound fetch() to CLOUD_URL via syncToCloud(). When that endpoint is
unset/unreachable/slow, the HTTP response blocked until the request settled
or timed out (20-90s+), unlike sibling routes (regenerate, /api/combos) that
never touch this side effect.

syncKeysToCloudIfEnabled() is now dispatched fire-and-forget instead of
awaited; its internal try/catch already logs failures, so cloud sync still
runs in the background without blocking the response.

src/app/api/keys/route.ts

@@ -93,8 +93,15 @@ export async function POST(request) {
       });
     }
 
-    // Auto sync to Cloud if enabled
-    await syncKeysToCloudIfEnabled();
+    // Auto sync to Cloud if enabled — fire-and-forget. Cloud sync is a
+    // background side-effect, not part of the key-creation contract, and it
+    // performs an outbound network call. Awaiting it here blocked the HTTP
+    // response on a slow/unreachable Cloud endpoint (e.g. a fresh/offline
+    // install with a misconfigured or unreachable CLOUD_URL): the request
+    // would hang until the fetch settled or timed out (#6570). Errors inside
+    // syncKeysToCloudIfEnabled() are already caught and logged internally, so
+    // this is safe to leave unawaited.
+    void syncKeysToCloudIfEnabled();
 
     return NextResponse.json(
       {