Frontend optimizations: SVG icons, remove updateFileIcons, unify rendering, scope translatePage

- Replace Font Awesome CDN with inline SVG system (icons.js + MutationObserver)
- Remove updateFileIcons() (~140 lines) - redundant with backend icon_class + MutationObserver
- Migrate favorites.js and recent.js to use shared ui.renderFolders/renderFiles (eliminate ~260 lines of duplicate rendering + per-item event listeners)
- Add view-mode aware click delegation for favorites/recent views
- Fix _createFileCard to apply icon_special_class
- Add translateElement(root) for scoped i18n translation
- Replace full-page translatePage() calls with scoped translateElement() or inline t()
- Remove redundant translatePage() calls in shared.js and auth.js
- Remove Alpine.js from Service Worker cache

static/js/shared.js

@@ -13,13 +13,7 @@ function checkAuthentication() {
 }
 
 document.addEventListener('DOMContentLoaded', async () => {
-    // ── i18n ──
-    if (window.i18n && window.i18n.init) {
-        await window.i18n.init();
-        setTimeout(() => {
-            if (window.i18n.translatePage) window.i18n.translatePage();
-        }, 500);
-    }
+    // ── i18n ── (translatePage is called automatically by i18n.js on init)
 
     function t(key, fallback) {
         return (window.i18n && window.i18n.t) ? window.i18n.t(key, fallback) : fallback;