Hosted rooms' instance IDs name their owner: <owner>-<2100000000+n>

The client takes a room's owner from the instance ID's first part; with 2100000000 there, the owner
couldn't decorate their hosted room (putting furniture on went to their home room instead).

Co-Authored-By: Claude Opus 5.5 <[email protected]>

apps/api/src/app.ts

@@ -227,7 +227,7 @@ export function createApp({ db, auth, imvu, realtime: rt, age: ageService, rooms
 
   const hostedView = ({ room: r, ownerName }: { room: typeof schema.hostedRoom.$inferSelect; ownerName: string }) => ({
     n: r.n,
-    instanceId: instanceId(r.n),
+    instanceId: instanceId(r.ownerImvuId, r.n),
     chatId: chatId(r.n),
     name: r.name,
     description: r.description,