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/RoomInput.tsx

@@ -679,15 +679,23 @@ export const RoomInput = forwardRef<HTMLDivElement, RoomInputProps>(
           submit();
         }
         if (isKeyHotkey('escape', evt)) {
-          evt.preventDefault();
+          // Only consume Escape (and stop it bubbling to the thread panel / room
+          // window handlers) when the composer actually has something to dismiss.
+          // If we did nothing, let Escape propagate so those handlers can run.
           if (autocompleteQuery) {
+            evt.preventDefault();
+            evt.stopPropagation();
             setAutocompleteQuery(undefined);
             return;
           }
-          setReplyDraft(undefined);
+          if (replyDraft) {
+            evt.preventDefault();
+            evt.stopPropagation();
+            setReplyDraft(undefined);
+          }
         }
       },
-      [submit, setReplyDraft, enterForNewline, autocompleteQuery, isComposing],
+      [submit, replyDraft, setReplyDraft, enterForNewline, autocompleteQuery, isComposing],
     );
 
     const handleKeyUp: KeyboardEventHandler = useCallback(