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/TileAvatar.module.css

@@ -18,20 +18,3 @@ Please see LICENSE in the repository root for full details.
   /* TODO: make this --cpd-color-fg-primary when available. */
   color: var(--cpd-color-text-primary);
 }
-
-/* [lotus #6] Wrap so the decoration can overlay the avatar precisely. */
-.container {
-  position: relative;
-  display: inline-flex;
-}
-
-/* [lotus #6] APNG/PNG profile decoration drawn over the in-call tile avatar.
-The decoration art shares the avatar's box (transparent padding, ring at the
-edges), matching how the host renders it elsewhere. */
-.lotusDecoration {
-  position: absolute;
-  inset: 0;
-  margin: auto;
-  pointer-events: none;
-  object-fit: contain;
-}