fix(threads): polls created from a thread composer land in the thread

PollCreator used the legacy 3-arg sendEvent (threadId null). Thread the
composer's threadRootId through and send like the sticker path.

Also (#41, same file): composer drafts are persisted as { userId, nodes }
and the restore path drops any draft with a different or missing userId.

Fixes #35

Co-Authored-By: Claude Opus 5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01PPmy3tPq869XDW4njjVaKA

src/app/features/room/PollCreator.tsx

@@ -25,10 +25,12 @@ import { useModalStyle } from '../../hooks/useModalStyle';
 interface PollCreatorProps {
   roomId: string;
   room: Room;
+  /** Set when the composer is inside a thread so the poll lands in that thread. */
+  threadRootId?: string;
   onClose: () => void;
 }
 
-export function PollCreator({ roomId, onClose }: PollCreatorProps) {
+export function PollCreator({ roomId, threadRootId, onClose }: PollCreatorProps) {
   const mx = useMatrixClient();
   const modalStyle = useModalStyle(440);
   const [question, setQuestion] = useState('');
@@ -85,7 +87,9 @@ export function PollCreator({ roomId, onClose }: PollCreatorProps) {
       const fallbackBody = [trimmedQuestion, ...filledOptions.map((o, i) => `${i + 1}. ${o}`)].join(
         '\n',
       );
-      await mx.sendEvent(roomId, 'm.poll.start' as any, {
+      // Pass the thread id explicitly (like the sticker path in RoomInput); the
+      // legacy 3-arg form always resolves to the main timeline.
+      await mx.sendEvent(roomId, threadRootId ?? null, 'm.poll.start' as any, {
         'm.poll': {
           question: { 'm.text': trimmedQuestion },
           answers: filledOptions.map((o, i) => ({ 'm.id': `${i}`, 'm.text': o })),