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/pages/auth/login/PasswordLoginForm.tsx

@@ -206,6 +206,7 @@ export function PasswordLoginForm({ defaultUsername, defaultEmail }: PasswordLog
           defaultValue={defaultUsername ?? defaultEmail}
           style={{ paddingRight: config.space.S300 }}
           name="usernameInput"
+          aria-label="Username or email"
           variant="Background"
           size="500"
           required
@@ -227,7 +228,7 @@ export function PasswordLoginForm({ defaultUsername, defaultEmail }: PasswordLog
         <Text as="label" size="L400" priority="300">
           Password
         </Text>
-        <PasswordInput name="passwordInput" variant="Background" size="500" outlined required />
+        <PasswordInput name="passwordInput" aria-label="Password" variant="Background" size="500" outlined required />
         <Box alignItems="Start" justifyContent="SpaceBetween" gap="200">
           {loginState.status === AsyncStatus.Error && (
             <>