perf(audit): emojibase lazy-split, SW precache, Prism subset, lazy images

- emojibase (~965 KB) is now fully lazy: plugins/emoji.ts loads compact data +
  shortcode maps via a memoized dynamic import (rejections reset the memo so a
  mid-deploy chunk 404 can retry); reaction labels degrade to the raw glyph
  until loaded. Consumers get FRESH array references on load (the module arrays
  populate in place — same-ref state updates would skip re-render and leave
  emoji search empty; reviewer-caught). Verified out of the eager graph.
- Service worker precaches hashed assets (workbox precacheAndRoute, 82 entries
  ~10.8 MB incl. the crypto wasm): repeat visits stop re-downloading the app.
  index.html is NOT precached — navigations stay network-first so deploys are
  picked up immediately; the media-auth fetch handler is untouched.
- ReactPrism: curated 21-language set — chunk 574 KB → 71 KB.
- Timeline inline images get loading="lazy".
- Removed dead dompurify (+types); sanitize-html is the real sanitizer.

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>

src/app/hooks/useRecentEmoji.ts

@@ -2,11 +2,26 @@ import { useEffect, useState } from 'react';
 import { ClientEvent, MatrixClient, MatrixEvent } from 'matrix-js-sdk';
 import { getRecentEmojis } from '../plugins/recent-emoji';
 import { AccountDataEvent } from '../../types/matrix/accountData';
-import { IEmoji } from '../plugins/emoji';
+import { IEmoji, loadEmojiData } from '../plugins/emoji';
 
 export const useRecentEmoji = (mx: MatrixClient, limit?: number): IEmoji[] => {
   const [recentEmoji, setRecentEmoji] = useState(() => getRecentEmojis(mx, limit));
 
+  // Recent emojis are resolved against the (now lazily loaded) emojibase data
+  // via getRecentEmojis. Recompute once loadEmojiData has populated it so the
+  // recent list fills in on first open.
+  useEffect(() => {
+    let alive = true;
+    loadEmojiData()
+      .then(() => {
+        if (alive) setRecentEmoji(getRecentEmojis(mx, limit));
+      })
+      .catch(() => undefined);
+    return () => {
+      alive = false;
+    };
+  }, [mx, limit]);
+
   useEffect(() => {
     const handleAccountData = (event: MatrixEvent) => {
       if (event.getType() !== AccountDataEvent.ElementRecentEmoji) return;