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/ThreadView.tsx

@@ -65,6 +65,8 @@ import * as roomViewCss from './RoomViewFollowing.css';
 import { Message, Reactions, EncryptedContent } from './message';
 import { Reply } from '../../components/message';
 import { RenderMessageContent } from '../../components/RenderMessageContent';
+import { EmojiConfettiOverlay } from './emoji-confetti/EmojiConfettiOverlay';
+import { useJumboEmojiConfetti } from './emoji-confetti/useJumboEmojiConfetti';
 import {
   LINKIFY_OPTS,
   factoryRenderLinkifyWithMention,
@@ -156,6 +158,8 @@ export function ThreadView({ room, threadRootId }: ThreadViewProps) {
   const [hour24Clock] = useSetting(settingsAtom, 'hour24Clock');
   const [dateFormatString] = useSetting(settingsAtom, 'dateFormatString');
   const [hideActivity] = useSetting(settingsAtom, 'hideActivity');
+  const { bursts: emojiConfettiBursts, removeBurst: removeEmojiConfettiBurst, handleJumboEmojiClick } =
+    useJumboEmojiConfetti(room);
 
   const showUrlPreview = room.hasEncryptionStateEvent() ? encUrlPreview : urlPreview;
   const direct = useIsDirectRoom();
@@ -638,6 +642,8 @@ export function ThreadView({ room, threadRootId }: ThreadViewProps) {
                 linkifyOpts={linkifyOpts}
                 outlineAttachment={messageLayout === MessageLayout.Bubble}
                 disabledEmbedPatterns={combinedEmbedFilters}
+                targetEventId={mEventId}
+                onJumboEmojiClick={handleJumboEmojiClick}
               />
             )}
           </EncryptedContent>
@@ -654,6 +660,8 @@ export function ThreadView({ room, threadRootId }: ThreadViewProps) {
             linkifyOpts={linkifyOpts}
             outlineAttachment={messageLayout === MessageLayout.Bubble}
             disabledEmbedPatterns={combinedEmbedFilters}
+            targetEventId={mEventId}
+            onJumboEmojiClick={handleJumboEmojiClick}
           />
         )}
       </Message>
@@ -759,6 +767,10 @@ export function ThreadView({ room, threadRootId }: ThreadViewProps) {
               {events.map((evt, idx, arr) => renderEvent(evt, idx, arr))}
             </Box>
           </Scroll>
+          <EmojiConfettiOverlay
+            bursts={emojiConfettiBursts}
+            onBurstComplete={removeEmojiConfettiBurst}
+          />
         </Box>
         <div className={roomViewCss.RoomViewBottomFloat}>
           <RoomViewTyping room={room} />