fix(a11y,bug): aria-labels on dialogs/buttons, useAlive GIF guard, typing timer fix

A11y:
- Add aria-label Close to RoomTopicViewer, ImagePackView close buttons
- Add aria-label Cancel to LeaveRoomPrompt cancel button
- Add aria-label to Send, Reply, Thread, Edit, React, Search, Mute, Download buttons
- Fix aria-pressed -> aria-expanded + aria-haspopup on menu anchor triggers
- Add aria-label to username/password auth inputs

BUG-21: Add useAlive unmount guard to handleGifSelect error path in RoomInput
BUG-22: Fix typing status timer accumulation with typingTimerRef

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

src/app/components/room-topic-viewer/RoomTopicViewer.tsx

@@ -26,7 +26,7 @@ export const RoomTopicViewer = as<
           {name}
         </Text>
       </Box>
-      <IconButton size="300" onClick={requestClose} radii="300">
+      <IconButton size="300" onClick={requestClose} radii="300" aria-label="Close">
         <Icon src={Icons.Cross} />
       </IconButton>
     </Header>