Decorations: keep them through IMVU's own room updates

After the owner saves, IMVU's server sends everyone the saved room ({"command": "SetRoomState"} from
admin on the chat's control mount), which has no decorations: the proxy now adds them to it, and takes
community products out of any outgoing one. A change notice from the hub also no longer empties the
remembered decorations while the new ones are asked for (a broadcast arriving meanwhile went through
without them).

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

internal/products/room.go

@@ -146,6 +146,13 @@ func userOf(userID string) int64 {
 // Incoming implements proxy.IMQWatcher: a T5DE user's whole outfit gets their community products added.
 func (p *Products) Incoming(c *proxy.IMQConn, m imq.Delivered) []byte {
 	chat := chatOf(m.Queue)
+	if chat != "" && m.Mount == "control" {
+		// IMVU's server sends everyone a room its owner saved (as IMVU has it: without decorations).
+		if out, changed := p.incomingControlScene(m.Message); changed {
+			return out
+		}
+		return m.Message
+	}
 	if chat == "" || m.Mount != "messages" {
 		return m.Message
 	}