feat(ux): forward to multiple rooms + live bookmark previews (P6-3)

Forward: checkbox multi-select room picker + "Send to N rooms" batch send
(Promise.allSettled). Full success auto-closes; partial failure keeps the dialog
open with a "Forwarded to X/N — failed: …" summary and prunes the selection to
only the failures (retry won't duplicate to already-sent rooms). Content builder
extracted to a unit-tested forwardContent.ts (edit-forwarding, reply-strip,
undecryptable-refused; 4 tests).

Bookmarks: BookmarksPanel resolves each saved message's live event (useRoomEvent)
so previews reflect edits and show a deleted indicator for redactions; the stored
snapshot stays as the fallback while loading, on fetch failure, or after leaving
the room. Stored bookmark shape unchanged.

Gates: tsc/eslint/prettier clean, build OK, 665 tests. Reviewed (dup-resend on
retry + Checkbox readOnly fixed).

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

src/app/features/bookmarks/BookmarksPanel.tsx

@@ -1,4 +1,5 @@
-import React, { ChangeEvent, useCallback, useEffect, useState } from 'react';
+import React, { ChangeEvent, ReactNode, useCallback, useEffect, useState } from 'react';
+import { Room } from 'matrix-js-sdk';
 import {
   Avatar,
   Box,
@@ -16,6 +17,8 @@ import {
 import classNames from 'classnames';
 import { useBookmarks, Bookmark } from '../../hooks/useBookmarks';
 import { useMatrixClient } from '../../hooks/useMatrixClient';
+import { useRoomEvent } from '../../hooks/useRoomEvent';
+import { MessageDeletedContent } from '../../components/message/content/FallbackContent';
 import { useRoomNavigate } from '../../hooks/useRoomNavigate';
 import { useMediaAuthentication } from '../../hooks/useMediaAuthentication';
 import { RoomAvatar } from '../../components/room-avatar';
@@ -42,9 +45,11 @@ type BookmarkItemProps = {
   bookmark: Bookmark;
   onJump: (roomId: string, eventId: string) => void;
   onRemove: (eventId: string) => void;
+  // Optional live-rendered preview node; falls back to the stored snapshot when absent.
+  preview?: ReactNode;
 };
 
-function BookmarkItem({ bookmark, onJump, onRemove }: BookmarkItemProps) {
+function BookmarkItem({ bookmark, onJump, onRemove, preview }: BookmarkItemProps) {
   const mx = useMatrixClient();
   const useAuthentication = useMediaAuthentication();
   const room = mx.getRoom(bookmark.roomId) ?? undefined;
@@ -104,18 +109,50 @@ function BookmarkItem({ bookmark, onJump, onRemove }: BookmarkItemProps) {
         style={{ justifyContent: 'flex-start', height: 'unset', padding: config.space.S200 }}
       >
         <Text className={css.BookmarkPreview} size="T200" priority="400">
-          {bookmark.previewText || '(no preview)'}
+          {preview ?? (bookmark.previewText || '(no preview)')}
         </Text>
       </Button>
     </Box>
   );
 }
 
+type LiveBookmarkItemProps = BookmarkItemProps & { room: Room };
+
+// Renders the same layout as BookmarkItem, but resolves the message body live so
+// edits (m.replace, applied by useRoomEvent) and redactions are reflected. The
+// stored snapshot (previewText) remains the fallback for loading/failed/empty states.
+function LiveBookmarkItem({ room, bookmark, onJump, onRemove }: LiveBookmarkItemProps) {
+  const liveEvent = useRoomEvent(room, bookmark.eventId, () =>
+    room.findEventById(bookmark.eventId),
+  );
+
+  const snapshot = bookmark.previewText || '(no preview)';
+  let preview: ReactNode = snapshot;
+
+  // undefined (loading) and null (fetch failed / not found) both keep the snapshot.
+  if (liveEvent) {
+    if (liveEvent.isRedacted()) {
+      preview = (
+        <MessageDeletedContent
+          reason={liveEvent.getUnsigned().redacted_because?.content?.reason as string | undefined}
+        />
+      );
+    } else {
+      // body is already the edited text since useRoomEvent applied m.replace.
+      const { body } = liveEvent.getContent();
+      preview = typeof body === 'string' && body ? body : snapshot;
+    }
+  }
+
+  return <BookmarkItem bookmark={bookmark} onJump={onJump} onRemove={onRemove} preview={preview} />;
+}
+
 type BookmarksPanelProps = {
   onClose: () => void;
 };
 
 export function BookmarksPanel({ onClose }: BookmarksPanelProps) {
+  const mx = useMatrixClient();
   const { bookmarks, removeBookmark } = useBookmarks();
   const { navigateRoom } = useRoomNavigate();
   const [filter, setFilter] = useState('');
@@ -228,14 +265,27 @@ export function BookmarksPanel({ onClose }: BookmarksPanelProps) {
             </Box>
           ) : (
             <Box className={css.BookmarksContent} direction="Column" gap="200">
-              {filtered.map((bk) => (
-                <BookmarkItem
-                  key={bk.eventId}
-                  bookmark={bk}
-                  onJump={handleJump}
-                  onRemove={removeBookmark}
-                />
-              ))}
+              {filtered.map((bk) => {
+                // Live render when the room is joined (useRoomEvent needs a non-null Room);
+                // otherwise fall back to the stored snapshot for rooms we've left.
+                const room = mx.getRoom(bk.roomId);
+                return room ? (
+                  <LiveBookmarkItem
+                    key={bk.eventId}
+                    room={room}
+                    bookmark={bk}
+                    onJump={handleJump}
+                    onRemove={removeBookmark}
+                  />
+                ) : (
+                  <BookmarkItem
+                    key={bk.eventId}
+                    bookmark={bk}
+                    onJump={handleJump}
+                    onRemove={removeBookmark}
+                  />
+                );
+              })}
             </Box>
           )}
         </Scroll>