fix: theme flash + language persistence on navigation

- Remove setTimeout re-application of theme in app-init.js that caused flash
- Fix quotations.html: add missing i18n.js and correct script load order
- Fix whatsapp.html: add missing app-init.js before sidebar.js
- Ensure i18n.js always loads before sidebar.js for proper translation

pos/static/js/app-init.js

@@ -167,12 +167,6 @@
         });
     }
 
-    // Also prevent any DOMContentLoaded theme switchers from overriding
-    // by re-applying our saved theme after a tick
-    setTimeout(function() {
-        document.documentElement.setAttribute('data-theme', savedTheme);
-    }, 100);
-
     // ─── Expose globally ───
     window.POS_USER = {
         name: name,