feat(video): explicit fullscreen button, simplify download pill sizing

- VideoBubble: add a Maximize2 fullscreen button at the top-right of
  the inline player (mirrors the download pill on the left), so the
  user explicitly opts into fullscreen instead of any tile click being
  promoted to one. Removed the outer onClick that opened fullscreen
  on any tap.
- AttachmentDownloadPill: drop the adaptive (cqw-based) sizing branch
  and the corresponding 'adaptive' prop. The pill is now a uniform
  30px tall in every host (album tile, single image, video tile),
  matching the design without needing query containers on parents.
- AlbumBubble: remove the now-unused 'adaptive' prop and the
  containerType: inline-size hook that supported it.

src/components/messageStream/bubbles/AlbumBubble.tsx

@@ -51,8 +51,6 @@ export function AlbumBubble({ post }: { post: Post }) {
                 top: `${tile.top * 100}%`,
                 width: `calc(${tile.width * 100}% - ${ALBUM_GAP}px)`,
                 height: `calc(${tile.height * 100}% - ${ALBUM_GAP}px)`,
-                // Query container so the download pill scales with this tile.
-                containerType: "inline-size",
               }}
             >
               <button
@@ -78,11 +76,7 @@ export function AlbumBubble({ post }: { post: Post }) {
                 ) : null}
               </button>
               {!isLastSlot ? (
-                <AttachmentDownloadPill
-                  postId={post.id}
-                  attachment={att}
-                  adaptive
-                />
+                <AttachmentDownloadPill postId={post.id} attachment={att} />
               ) : null}
             </div>
           );