feat(middleware): improve private mode handling in CheckPrivateModeMiddleware

- Refactored the logic for redirecting to maintenance mode.
- Added check for authenticated users when private mode is enabled.
- Ensured non-authenticated users are redirected appropriately when accessing maintenance route.

app/Http/Middleware/CheckPrivateModeMiddleware.php

@@ -14,9 +14,15 @@ public function handle(Request $request, Closure $next)
         $userSecretInput = $request->input('secret');
         $secretIsUsable = ! empty($privateModeSecret) && $privateModeSecret === $userSecretInput;
 
-        if ($privateModeEnabled && ! $secretIsUsable) {
+        if ($privateModeEnabled) {
+            if (! $secretIsUsable && ! auth()->check()) {
+                if (! $request->is('maintenance')) {
                     return redirect()->route('maintenance');
-        } elseif (! $privateModeEnabled && $request->is('maintenance')) {
+                }
+            }
+        }
+
+        if (! $privateModeEnabled && $request->is('maintenance') && ! auth()->check()) {
             return redirect()->route('index');
         }