feat: Remind Me Later, mobile bookmarks, bug fixes, and doc cleanup

Features:
- Remind Me Later: message context menu item opens a preset time picker
  (20 min / 1 hr / 3 hr / tomorrow 9am); reminders persist to Matrix
  account data (io.lotus.reminders); ReminderMonitor fires a Lotus Toast
  when due, checks every 30s and on tab focus
- Mobile Bookmarks: BookmarksPanel now renders on all screen sizes;
  passes isMobile prop for full-screen absolute overlay on mobile

Bug fixes:
- usePan.ts: memory leak from stale closure in document listener cleanup
- EventReaders.tsx: replace hardcoded hex colors with TDS CSS variables
- CallControls.tsx: replace hardcoded hex colors with TDS CSS variables
- CustomHtml.css.ts: replace hardcoded yellow/black highlight with theme tokens

Docs:
- LOTUS_TODO.md: restore deleted content (Confirmed facts table, Pending
  Audits, P5-30 completed status, full feature descriptions), keep new
  additions (P4-7/8/9, P5-41–57, Implementation Reference), eliminate
  duplicate sections
- LOTUS_BUGS.md: merge RESILIENCE_AUDIT.md findings into Architectural &
  Resilience Audit table; delete RESILIENCE_AUDIT.md
- Remove stale LOTUS_DENOISE_ENGINEERING_REVIEW.md and LOTUS_TODO_REFERENCE.md

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

src/app/hooks/useReminders.ts

@@ -0,0 +1,75 @@
+import { useCallback, useEffect, useState } from 'react';
+import { MatrixClient } from 'matrix-js-sdk';
+import { useMatrixClient } from './useMatrixClient';
+import { useAccountDataCallback } from './useAccountDataCallback';
+
+export type Reminder = {
+  roomId: string;
+  eventId: string;
+  timestamp: number;
+  message: string;
+};
+
+const REMINDERS_KEY = 'io.lotus.reminders';
+
+type RemindersContent = {
+  reminders: Reminder[];
+};
+
+function readReminders(mx: MatrixClient): Reminder[] {
+  return (
+    (mx.getAccountData(REMINDERS_KEY as any)?.getContent() as RemindersContent | undefined)
+      ?.reminders ?? []
+  );
+}
+
+export function useReminders(): {
+  reminders: Reminder[];
+  addReminder: (r: Reminder) => Promise<void>;
+  removeReminder: (eventId: string, timestamp: number) => Promise<void>;
+  getReminders: () => Reminder[];
+} {
+  const mx = useMatrixClient();
+  const [reminders, setReminders] = useState<Reminder[]>(() => readReminders(mx));
+
+  useAccountDataCallback(
+    mx,
+    useCallback(
+      (evt) => {
+        if (evt.getType() === REMINDERS_KEY) {
+          setReminders(evt.getContent<RemindersContent>()?.reminders ?? []);
+        }
+      },
+      [setReminders],
+    ),
+  );
+
+  // Re-read on mx change
+  useEffect(() => {
+    setReminders(readReminders(mx));
+  }, [mx]);
+
+  const addReminder = useCallback(
+    async (r: Reminder) => {
+      const current = readReminders(mx);
+      const next = [...current, r];
+      await (mx as any).setAccountData(REMINDERS_KEY, { reminders: next });
+    },
+    [mx],
+  );
+
+  const removeReminder = useCallback(
+    async (eventId: string, timestamp: number) => {
+      const current = readReminders(mx);
+      const next = current.filter(
+        (r) => !(r.eventId === eventId && r.timestamp === timestamp),
+      );
+      await (mx as any).setAccountData(REMINDERS_KEY, { reminders: next });
+    },
+    [mx],
+  );
+
+  const getReminders = useCallback(() => reminders, [reminders]);
+
+  return { reminders, addReminder, removeReminder, getReminders };
+}