fix(audit): correctness wave — ghost sends, Escape coordination, panel exclusion

- ScheduledMessagesTray: cancel prunes local state ONLY on confirmed server
  cancel; failures keep the item + show an inline error (was: a failed cancel
  looked cancelled but still sent at the scheduled time).
- Escape semantics: the composer consumes Escape (preventDefault+stopPropagation)
  iff autocomplete is open or a reply draft is set; the thread panel and Room's
  markAsRead act only on unconsumed Escape, and markAsRead defers entirely while
  a thread panel is open (listener order made it fire before the panel closed).
- Room: thread panel / media gallery are mutually exclusive (most-recently-
  opened wins); on mobile at most one right panel renders (thread > gallery >
  members) instead of stacked fullscreen overlays.
- RemindMeDialog: busy-disabled presets (no more double-click duplicates),
  try/catch with inline error, close only on success.
- ThreadTimeline: "Jump to Latest" floating chip when scrolled up (RoomTimeline
  idiom).

From the 4-auditor deep-audit wave; reviewer-verified.

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>

src/app/features/room/thread/ThreadPanel.tsx

@@ -123,6 +123,10 @@ export function ThreadPanel({ room, threadId, requestClose }: ThreadPanelProps)
     useCallback(
       (evt) => {
         if (isKeyHotkey('escape', evt)) {
+          // The composer preventDefaults Escape when it consumes it (dismissing
+          // autocomplete / clearing a reply draft). Don't close the panel in
+          // that case — only when Escape wasn't already handled.
+          if (evt.defaultPrevented) return;
           evt.preventDefault();
           evt.stopPropagation();
           requestClose();

src/app/features/room/thread/ThreadTimeline.css.ts

@@ -11,6 +11,15 @@ export const ThreadTimelineContent = style({
   padding: `${config.space.S400} 0`,
 });
 
+export const ThreadTimelineFloat = style({
+  position: 'absolute',
+  bottom: config.space.S400,
+  left: '50%',
+  transform: 'translateX(-50%)',
+  zIndex: 1,
+  minWidth: 'max-content',
+});
+
 export const ThreadCentered = style({
   height: '100%',
   padding: config.space.S700,

src/app/features/room/thread/ThreadTimeline.tsx

@@ -29,7 +29,7 @@ import { Editor } from 'slate';
 import { ReactEditor } from 'slate-react';
 import to from 'await-to-js';
 import { useAtomValue, useSetAtom } from 'jotai';
-import { Badge, Box, Line, Scroll, Spinner, Text, color, config } from 'folds';
+import { Badge, Box, Chip, Icon, Icons, Line, Scroll, Spinner, Text, color, config } from 'folds';
 import classNames from 'classnames';
 import { Opts as LinkifyOpts } from 'linkifyjs';
 import { eventWithShortcode, factoryEventSentBy, getMxIdLocalPart } from '../../../utils/matrix';
@@ -459,6 +459,14 @@ export function ThreadTimeline({ room, thread, editor }: ThreadTimelineProps) {
     }
   }, [scrollToBottomCount]);
 
+  const handleJumpToBottom = useCallback(() => {
+    scrollToBottomRef.current.count += 1;
+    scrollToBottomRef.current.smooth = true;
+    // Flip atBottom so the layout effect re-runs (count re-read) and live
+    // events resume sticking to the bottom.
+    setAtBottom(true);
+  }, []);
+
   // Scroll in-place editor into view.
   useEffect(() => {
     if (editId) {
@@ -949,6 +957,19 @@ export function ThreadTimeline({ room, thread, editor }: ThreadTimelineProps) {
           <span ref={atBottomAnchorRef} />
         </Box>
       </Scroll>
+      {!atBottom && (
+        <Box className={css.ThreadTimelineFloat} justifyContent="Center" alignItems="Center">
+          <Chip
+            variant="SurfaceVariant"
+            radii="Pill"
+            outlined
+            before={<Icon size="50" src={Icons.ArrowBottom} />}
+            onClick={handleJumpToBottom}
+          >
+            <Text size="L400">Jump to Latest</Text>
+          </Chip>
+        </Box>
+      )}
       {editHistoryEvent && (
         <EditHistoryModal
           room={room}