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/RoomInput.tsx

@@ -802,7 +802,7 @@ export const RoomInput = forwardRef<HTMLDivElement, RoomInputProps>(
                   <Icon src={Icons.Pin} size="100" />
                 )}
               </IconButton>
-              <IconButton onClick={submit} variant="SurfaceVariant" size="300" radii="300">
+              <IconButton onClick={submit} variant="SurfaceVariant" size="300" radii="300" aria-label="Send message">
                 <Icon src={Icons.Send} />
               </IconButton>
             </>

src/app/features/room/RoomTimeline.tsx

@@ -341,7 +341,7 @@ const useTimelinePagination = (
         })
       );
       if (err) {
-        // TODO: handle pagination error.
+        fetching = false;
         return;
       }
       const fetchedTimeline =
@@ -622,7 +622,8 @@ export function RoomTimeline({ room, eventId, roomInputRef, editor }: RoomTimeli
             // Check if the document is in focus (user is actively viewing the app),
             // and either there are no unread messages or the latest message is from the current user.
             // If either condition is met, trigger the markAsRead function to send a read receipt.
-            requestAnimationFrame(() => markAsRead(mx, mEvt.getRoomId()!, hideActivity));
+            const _roomId = mEvt.getRoomId();
+          if (_roomId) requestAnimationFrame(() => markAsRead(mx, _roomId, hideActivity));
           }
 
           if (!document.hasFocus() && !unreadInfo) {
@@ -826,7 +827,7 @@ export function RoomTimeline({ room, eventId, roomInputRef, editor }: RoomTimeli
       const evtTimeline = getEventTimeline(room, readUptoEventId);
       const absoluteIndex =
         evtTimeline && getEventIdAbsoluteIndex(linkedTimelines, evtTimeline, readUptoEventId);
-      if (absoluteIndex) {
+      if (typeof absoluteIndex === 'number') {
         scrollToItem(absoluteIndex, {
           behavior: 'instant',
           align: 'start',

src/app/features/room/RoomView.tsx

@@ -1,4 +1,4 @@
-import React, { useCallback, useRef } from 'react';
+import React, { useCallback, useMemo, useRef } from 'react';
 import { Box, Text, config } from 'folds';
 import { EventType } from 'matrix-js-sdk';
 import { ReactEditor } from 'slate-react';
@@ -98,8 +98,13 @@ export function RoomView({ eventId }: { eventId?: string }) {
     )
   );
 
+    const chatBgStyle = useMemo(
+    () => getChatBg(lotusTerminal && chatBackground === 'none' ? 'tactical' : chatBackground, isDark),
+    [chatBackground, lotusTerminal, isDark]
+  );
+
   return (
-    <Page ref={roomViewRef} style={getChatBg(lotusTerminal && chatBackground === 'none' ? 'tactical' : chatBackground, isDark)}>
+    <Page ref={roomViewRef} style={chatBgStyle}>
       <Box grow="Yes" direction="Column">
         <RoomTimeline
           key={roomId}

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;