feat: bookmarks, message scheduling, image compression, room insights

P3-1: Message Bookmarks — right-click any message to bookmark; saved to
io.lotus.bookmarks account data (max 500, syncs across devices); star
icon in sidebar opens BookmarksPanel with filter, Jump-to-message, and
remove buttons; reactive to AccountData events

P3-2: Message Scheduling (MSC4140) — clock button next to send opens
ScheduleMessageModal with datetime-local picker; validates ≥1 min future;
calls PUT org.matrix.msc4140 delayed event API; collapsible
ScheduledMessagesTray above composer lists pending messages with cancel;
local Jotai atom tracks scheduled messages per room

P3-3: File Upload Compression — opt-in checkbox per JPEG/PNG file ≥200KB
in upload preview; canvas API compresses at 0.82 quality; shows before/
after size estimate; compressed blob used in upload when checked

P3-7: Room Insights — new Insights tab in room settings; top 5 active
members (bar chart), top 5 reactions (chips), media breakdown (4 tiles),
24-hour activity heatmap (CSS bar chart); all from local cache only with
disclaimer banner; never the first tab shown

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

src/app/features/room-settings/RoomSettings.tsx

@@ -20,6 +20,7 @@ import { DeveloperTools } from '../common-settings/developer-tools';
 import { ExportRoomHistory } from './ExportRoomHistory';
 import { RoomActivityLog } from './RoomActivityLog';
 import { RoomServerACL } from './RoomServerACL';
+import { RoomInsights } from './RoomInsights';
 import { usePowerLevels, readPowerLevel } from '../../hooks/usePowerLevels';
 import { useRoomCreators } from '../../hooks/useRoomCreators';
 import { StateEvent } from '../../../types/matrix/room';
@@ -66,6 +67,11 @@ const BASE_MENU_ITEMS: RoomSettingsMenuItem[] = [
     name: 'Activity',
     icon: Icons.RecentClock,
   },
+  {
+    page: RoomSettingsPage.InsightsPage,
+    name: 'Insights',
+    icon: Icons.Info,
+  },
 ];
 
 const SERVER_ACL_MENU_ITEM: RoomSettingsMenuItem = {
@@ -218,6 +224,9 @@ export function RoomSettings({ initialPage, requestClose }: RoomSettingsProps) {
       {activePage === RoomSettingsPage.ServerACLPage && (
         <RoomServerACL requestClose={handlePageRequestClose} />
       )}
+      {activePage === RoomSettingsPage.InsightsPage && (
+        <RoomInsights requestClose={handlePageRequestClose} />
+      )}
     </PageRoot>
   );
 }