lotus(#6): render decoration in MediaView; fix store lifecycle

Review found in-call tiles use MediaView->Avatar, not TileAvatar, so the
decoration never rendered in-call (CRITICAL). Move the overlay into
MediaView, gated on the avatar's own visibility (!(video && videoEnabled))
so it never floats over live video; revert the TileAvatar changes.
Also ref-count the io.lotus.decorations registration (one shared handler,
no double-reply) and stop clearing the map on teardown so a transient
remount doesn't drop decorations (HIGH/MED).

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>

src/tile/MediaView.tsx

@@ -22,6 +22,7 @@ import { ErrorSolidIcon } from "@vector-im/compound-design-tokens/assets/web/ico
 
 import styles from "./MediaView.module.css";
 import { Avatar } from "../Avatar";
+import { useLotusDecoration } from "../lotus/lotusDecorations";
 import { RaisedHandIndicator } from "../reactions/RaisedHandIndicator";
 import {
   showConnectionStats as showConnectionStatsSetting,
@@ -91,6 +92,7 @@ export const MediaView: FC<Props> = ({
   ...props
 }) => {
   const { t } = useTranslation();
+  const decoration = useLotusDecoration(userId);
   const [handRaiseTimerVisible] = useSetting(showHandRaisedTimer);
   const [showConnectionStats] = useSetting(showConnectionStatsSetting);
 
@@ -137,6 +139,17 @@ export const MediaView: FC<Props> = ({
           })}
           style={{ display: video && videoEnabled ? "none" : "initial" }}
         />
+        {decoration && !(video && videoEnabled) && (
+          // [lotus #6] Profile decoration overlay, shown only when the avatar
+          // is visible (i.e. not when live video is showing). Pushed by the
+          // host via io.lotus.decorations; undefined unless opted in.
+          <img
+            className={styles.lotusDecoration}
+            src={decoration}
+            alt=""
+            aria-hidden
+          />
+        )}
         {video?.publication !== undefined && (
           <VideoTrack
             trackRef={video}