Serve T5DE-hosted rooms; a second client instance's own data

Hosted rooms (internal/hosted): room calls for them answered here, their IMQ queues served (a new
proxy.IMQRouter hook takes them out of subscriptions to IMVU), chat relayed through the hub's
WebSocket (hub.Client gains Send, OnRoom and OnConnect), the room list extended, room products
checked against the real owner, and anything else naming a hosted room kept from IMVU.

T5DE_INSTANCE gives a second client's proxy its own data folder and log.

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

README.md

@@ -80,6 +80,16 @@ that aren't here yet (up to 15 seconds) so they can be shown and tried on. Buyin
 (`api/service/shop/svc_catalog_purchase.php`) adds them to the person's hub library; IMVU products in the same
 purchase go on to IMVU without them.
 
+T5DE-hosted rooms (`internal/hosted`, t5de-hub's `docs/hosted-rooms.md`): rooms living on the hub, with instance IDs
+`2100000000-<n>` and chat IDs `2100000000+n`. The proxy answers the client's room calls for them (`getRoomCardInfo`,
+`getOrMakeChat`, `getRoomState`, `setRoomState`, `getParticipants`, `terminateChat`), serves their IMQ queues
+(`/chat/<id>`, `inv:/room/room-<id>`, `room_occupancy/<id>`: subscriptions answered here through `proxy.IMQRouter`,
+chat to and from the hub over its WebSocket), adds them to the room list, checks the room's products against its real
+owner (`authorizeProducts2`), and answers any other request to IMVU naming one ("not found") rather than send it.
+
+`T5DE_INSTANCE=<name>` (set by the client's `t5de-instances` patch for a second client run beside the first) keeps
+the proxy's data in `%APPDATA%\T5DE-<name>\proxy` and its log in `t5de-proxy-<name>.log`.
+
 For finding out what IMVU's APIs send, `T5DE_PROXY_DUMP=<text>` logs the request and response bodies of requests
 whose path contains it (test accounts only: bodies hold personal data). In Git Bash, keep the value from starting
 with `/` (or set `MSYS_NO_PATHCONV=1`), or it's turned into a Windows path.