Support Quest Platform SDK auth with oculusId fallback

When the Data Use Checkup hasn't granted numeric ID access, the SDK
returns oculusId (string username) instead. This makes nonce optional,
skips nonce verification for non-numeric userIds, and uses oculusId as
the metaId when numeric ID is unavailable.

src/types/api.ts

@@ -1,6 +1,7 @@
 // ── Auth ──────────────────────────────────────────────────
 export interface MetaCallbackBody {
-  code: string;
+  userId: string;
+  nonce?: string;
   deviceInfo?: string;
 }