Switch PHP views to Twig and add 2FA/UI enhancements

Migrate many view templates from raw PHP to Twig and modernize UI/UX for 2FA and settings. Controllers updated to provide avatar data and two-factor info (ProfileController, UserController) and SettingsController now includes timezone lists, notification preset selection, cron path, cached update state and rollback availability. ErrorHandler now attempts to render error pages via a new Core\TwigService with a safe fallback to raw PHP views. TwoFactorService generation silences deprecated warnings during QR code creation. Numerous .php view files were removed and replaced with .twig equivalents (2fa setup/verify/backup-codes and many auth, dashboard, domains, errors, layout, users, tags, tld-registry, etc.), and core/TwigService was added. These changes move the app toward a Twig-based templating system, improve 2FA flows, surface avatar images in lists/profiles, and make error rendering more robust.

core/Router.php

@@ -72,7 +72,12 @@ class Router
                 // Silently fail if logging is not available
             }
             
-            require_once __DIR__ . '/../app/Views/errors/404.php';
+            $twigPath = __DIR__ . '/../app/Views/errors/404.twig';
+            if (file_exists($twigPath)) {
+                echo TwigService::getInstance()->render('errors/404.twig');
+            } else {
+                require_once __DIR__ . '/../app/Views/errors/404.php';
+            }
             return;
         }