Bug fixes, security hardening, and performance improvements

- BUG-16: Fixed pagination deadlock (fetching flag stuck on error path)
- BUG-17: Fixed absoluteIndex===0 falsy check skipping unread jump
- BUG-19: Fixed mEvt.getRoomId()! non-null assertion crash
- BUG-20: Wrapped getSettings()/setSettings() in try/catch for corrupt localStorage
- SEC: Replaced randomStr() Math.random() with crypto.getRandomValues() CSPRNG
- SEC: Fixed afterLoginRedirectPath open redirect validation
- SEC: Narrowed OSM iframe sandbox to scripts-only (removed allow-same-origin)
- Perf-2: Memoized selectAtom in useSetting (prevented new atom ref per render)
- Perf-4: Fixed typingMembers setTimeout leak (tracked timers per user/room)
- Perf-8: Memoized getChatBg() result in RoomView (not inline in JSX)
- Perf-12: Replaced body.class * font-family with body.class (inherited)
- Perf-15: Memoized typingNames array chain in RoomViewTyping
- Perf-9: Added blob URL cleanup useEffect in AudioContent
- BUG: Fixed forEach(async) -> Promise.all in useCommands join handler
- BUG: Fixed useCompositionEndTracking missing dependency array
- A11y: Fixed spoiler button aria-pressed + keyboard handler
- A11y: Added aria-label to Send message button
- Build: Set sourcemap:false, removed netlify.toml from copyFiles

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

src/app/features/room/RoomViewTyping.tsx

@@ -1,4 +1,4 @@
-import React from 'react';
+import React, { useMemo } from 'react';
 import { Box, Icon, IconButton, Icons, Text, as } from 'folds';
 import { Room } from 'matrix-js-sdk';
 import classNames from 'classnames';
@@ -20,12 +20,18 @@ export const RoomViewTyping = as<'div', RoomViewTypingProps>(
     const mx = useMatrixClient();
     const typingMembers = useRoomTypingMember(room.roomId);
 
-    const typingNames = typingMembers
-      .filter((receipt) => receipt.userId !== mx.getUserId())
-      .map(
-        (receipt) => getMemberDisplayName(room, receipt.userId) ?? getMxIdLocalPart(receipt.userId)
-      )
-      .reverse();
+    const myUserId = mx.getUserId();
+    const typingNames = useMemo(
+      () =>
+        typingMembers
+          .filter((receipt) => receipt.userId !== myUserId)
+          .map(
+            (receipt) =>
+              getMemberDisplayName(room, receipt.userId) ?? getMxIdLocalPart(receipt.userId)
+          )
+          .reverse(),
+      [typingMembers, myUserId, room]
+    );
 
     if (typingNames.length === 0) {
       return null;