feat: presence fix, voice ringing fix, user private notes + doc updates

- usePresenceUpdater: replace stale closure with readStatus() called at
  invocation time so changing custom status in Profile Settings is never
  silently overwritten by subsequent activity events
- CallEmbedProvider: fix m.space.parent state-key lookup by switching
  getStateEvent → getStateEvents (plural); space channel voice rooms no
  longer trigger the incoming-call ring/animation
- Add useUserNotes hook (io.lotus.user_notes account data, reactive via
  useAccountDataCallback, 500-char limit, cross-device sync)
- UserRoomProfile: add UserPrivateNotes textarea with 800ms debounced
  auto-save, saving indicator, char counter when <100 chars remain;
  shown only when viewing another user's profile
- LOTUS_FEATURES.md: add Private Notes section, Status Revert fix note,
  animation improvements subsection, Seasonal Themes section
- LOTUS_BUGS.md: mark presence revert + voice ringing bugs as resolved
- README.md + landing/index.html: document all new June 2026 features

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

src/app/components/CallEmbedProvider.tsx

@@ -54,7 +54,7 @@ import { getChatBg } from '../features/lotus/chatBackground';
 import { useTheme, ThemeKind } from '../hooks/useTheme';
 import { useSetting } from '../state/hooks/settings';
 import { settingsAtom } from '../state/settings';
-import { getStateEvent, getMemberDisplayName } from '../utils/room';
+import { getStateEvent, getStateEvents, getMemberDisplayName } from '../utils/room';
 import { StateEvent } from '../../types/matrix/room';
 import { getPowersLevelFromMatrixEvent } from '../hooks/usePowerLevels';
 import { getRoomCreatorsForRoomId } from '../hooks/useRoomCreators';
@@ -329,7 +329,10 @@ function IncomingCallListener({ callEmbed, joined }: IncomingCallListenerProps)
       // Space voice channels and public rooms fire room-level RTC notifications
       // whenever anyone joins — ringing every member is incorrect behaviour.
       const isDirect = directs.has(room.roomId);
-      const isSpaceChild = !!getStateEvent(room, StateEvent.SpaceParent);
+      // m.space.parent uses the parent space ID as the state key, so getStateEvent
+      // (which defaults to stateKey='') always returns undefined. Use getStateEvents
+      // (no key filter) to detect any space parent relationship.
+      const isSpaceChild = getStateEvents(room, StateEvent.SpaceParent).length > 0;
       const joinRule = room.getJoinRule();
       const isPrivateGroup =
         !isSpaceChild &&