T5 furniture and poses in IMVU rooms (decorations)

Community products are taken out of rooms their owners save and broadcast, kept on the hub per room,
and added back when anyone with T5DE loads the room or gets its owner's broadcast; the hub's decor
notice resends the room with the new ones. Placements are stored with the hub's product ID.

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

README.md

@@ -87,6 +87,13 @@ T5DE-hosted rooms (`internal/hosted`, t5de-hub's `docs/hosted-rooms.md`): rooms
 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.
 
+Decorations (`internal/products/decor.go`): community furniture and poses in IMVU rooms. They're taken out of the
+room its owner saves (`test.setRoomState`) and broadcasts (`*imvu:setRoomState`, a zlib-compressed scene) so IMVU
+keeps the base room, and stored on the hub for that room (`PUT /api/v1/decorations/<instance>`; placements name their
+product, stored as the hub's ID). Loading the room (`test.getRoomState`, the hub asked at the same time) and the owner's
+incoming broadcasts get them added back as local IDs; the hub's `decor` notice makes the proxy give the client the room
+again with the new ones.
+
 `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`.