fix: correct event type in ForwardMessageDialog and poll response format

- ForwardMessageDialog: use sendEvent instead of sendMessage to preserve
  the original event type (stickers, polls, etc.)
- PollContent: use m.selections for stable m.poll.response (per spec),
  was incorrectly using m.responses

src/app/components/message/content/PollContent.tsx

@@ -60,7 +60,7 @@ export function PollContent({
     if (isStable) {
       mx.sendEvent(roomId, 'm.poll.response' as any, {
         'm.relates_to': { rel_type: 'm.reference', event_id: eventId },
-        'm.responses': [{ 'm.id': answerId }],
+        'm.selections': [answerId],
       });
     } else {
       mx.sendEvent(roomId, 'org.matrix.msc3381.poll.response' as any, {