implement directory listing navigation

src/nex.php

@@ -220,11 +220,28 @@ $server->start(
 
                 foreach ((array) scandir($goal) as $link)
                 {
-                    // Skip hidden entities and make sure the destination is accessible
-                    if (!str_starts_with($link, '.') && is_readable($goal . $link))
+                    // Skip system entities
+                    if (str_starts_with($link, '.'))
                     {
+                        // Keep parent navigation entities only
+                        if ($link == '..' && $parent = realpath($goal . $link))
+                        {
+                            if (str_starts_with($parent . DIRECTORY_SEPARATOR, NEXT_PATH))
+                            {
+                                if (is_readable($parent))
+                                {
+                                    $links[] = '=> ../';
+                                }
+                            }
+                        }
+
+                        continue;
+                    }
+
                     // Directory
-                        if (is_dir($link))
+                    if (is_dir($goal . $link))
+                    {
+                        if (is_readable($goal . $link))
                         {
                             $links[] = sprintf(
                                 '=> %s/',
@@ -234,8 +251,11 @@ $server->start(
                             );
                         }
 
+                        continue;
+                    }
+
                     // File
-                        else
+                    if (is_readable($goal . $link))
                     {
                         $links[] = sprintf(
                             '=> %s',
@@ -245,7 +265,6 @@ $server->start(
                         );
                     }
                 }
-                }
 
                 $response = implode(
                     PHP_EOL,