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/components/editor/autocomplete/EmoticonAutocomplete.tsx

@@ -1,4 +1,4 @@
-import React, { KeyboardEvent as ReactKeyboardEvent, useEffect, useMemo } from 'react';
+import React, { KeyboardEvent as ReactKeyboardEvent, useEffect, useMemo, useState } from 'react';
 import { Editor } from 'slate';
 import { Box, MenuItem, Text, toRem } from 'folds';
 import { Room } from 'matrix-js-sdk';
@@ -11,7 +11,7 @@ import { onTabPress } from '../../../utils/keyboard';
 import { createEmoticonElement, moveCursor, replaceWithElement } from '../utils';
 import { useRecentEmoji } from '../../../hooks/useRecentEmoji';
 import { useRelevantImagePacks } from '../../../hooks/useImagePacks';
-import { IEmoji, emojis } from '../../../plugins/emoji';
+import { IEmoji, emojis, loadEmojiData } from '../../../plugins/emoji';
 import { useKeyDown } from '../../../hooks/useKeyDown';
 import { mxcUrlToHttp } from '../../../utils/matrix';
 import { useMediaAuthentication } from '../../../hooks/useMediaAuthentication';
@@ -47,13 +47,32 @@ export function EmoticonAutocomplete({
   const imagePacks = useRelevantImagePacks(ImageUsage.Emoticon, imagePackRooms);
   const recentEmoji = useRecentEmoji(mx, 20);
 
+  // Lazily load emojibase data (see plugins/emoji `loadEmojiData`). Until it
+  // resolves, `emojis` is empty and autocomplete matches only custom-emoji
+  // packs; the unicode emoji list fills in once loaded.
+  const [loadedEmojis, setLoadedEmojis] = useState<IEmoji[]>(() => emojis);
+  useEffect(() => {
+    let alive = true;
+    loadEmojiData()
+      // Fresh array reference: loadEmojiData populates the module-level array
+      // IN PLACE, so state set to the same ref would bail out of re-rendering
+      // and the search list would never gain the unicode emojis.
+      .then((loaded) => {
+        if (alive) setLoadedEmojis(loaded.emojis.slice());
+      })
+      .catch(() => undefined);
+    return () => {
+      alive = false;
+    };
+  }, []);
+
   const searchList = useMemo(() => {
     const list: Array<EmoticonSearchItem> = [];
     return list.concat(
       imagePacks.flatMap((pack) => pack.getImages(ImageUsage.Emoticon)),
-      emojis,
+      loadedEmojis,
     );
-  }, [imagePacks]);
+  }, [imagePacks, loadedEmojis]);
 
   const [result, search, resetSearch] = useAsyncSearch(
     searchList,