Add emoji confetti bursts and component playground.

Support app.relay.emoji_confetti on jumbo emoji clicks with canvas physics,
per-emoji particle profiles, and a fixed overlay that does not affect scroll.
Also add a Vite playground for live component previews and theme hover preview.

src/app/features/room/emoji-confetti/useJumboEmojiConfetti.ts

@@ -0,0 +1,37 @@
+import { KeyboardEvent, MouseEvent, useCallback } from 'react';
+import { Room } from 'matrix-js-sdk';
+import { useMatrixClient } from '../../../hooks/useMatrixClient';
+import { resolveClickedEmoji } from './resolveClickedEmoji';
+import { sendEmojiConfettiEvent } from './sendEmojiConfetti';
+import { useEmojiConfetti } from './useEmojiConfetti';
+
+export function useJumboEmojiConfetti(room: Room) {
+  const mx = useMatrixClient();
+  const { bursts, removeBurst, triggerLocalBurst, registerOwnEventId } = useEmojiConfetti(room);
+
+  const handleJumboEmojiClick = useCallback(
+    (targetEventId: string, body: string, event: MouseEvent<HTMLElement> | KeyboardEvent<HTMLElement>) => {
+      const clicked = resolveClickedEmoji(event, body);
+      if (!clicked) return;
+
+      const emojis = [clicked.emoji];
+
+      triggerLocalBurst(targetEventId, emojis, clicked.origin);
+      sendEmojiConfettiEvent(mx, room.roomId, targetEventId, emojis)
+        .then((response) => {
+          const eventId = response?.event_id;
+          if (eventId) registerOwnEventId(eventId);
+        })
+        .catch((error) => {
+          console.error('[emoji-confetti] Failed to send confetti event:', error);
+        });
+    },
+    [mx, registerOwnEventId, room.roomId, triggerLocalBurst]
+  );
+
+  return {
+    bursts,
+    removeBurst,
+    handleJumboEmojiClick,
+  };
+}