fix: dompurify 2.5.9->3.4.5 (XSS), emojibase chunk, husky prepare

- dompurify updated to 3.4.5 to fix 7 XSS/prototype-pollution CVEs
- emojibase-data added to manualChunks: splits 856 kB out of the main
  bundle, reducing it from 1.8 MB to 932 kB
- husky prepare script updated from deprecated "husky install" to "husky"

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

vite.config.js

@@ -162,6 +162,7 @@ export default defineConfig({
           if (id.includes('node_modules/jotai')) return 'jotai';
           if (id.includes('node_modules/immer')) return 'immer';
           if (id.includes('node_modules/folds')) return 'folds';
+          if (id.includes('node_modules/emojibase')) return 'emojibase';
         },
       },
     },