added moderation portal with admin authentification and seperate styling

public/api/auth.php

@@ -0,0 +1,41 @@
+<?php
+// =====================================================================
+// Admin Authentication Helper
+// Provides simple Password-based Session Authentication for the
+// Moderation Page. Uses ADMIN_PASSWORD from .env File.
+// ToDo: Replace with full User Authentication in Phase 3-3.
+// =====================================================================
+
+// Reads Admin Password from Environment
+function get_admin_password() {
+    return getenv('ADMIN_PASSWORD');
+}
+
+// Checks if current Session is authenticated as Admin
+function is_admin() {
+    return isset($_SESSION['is_admin']) && $_SESSION['is_admin'] === true;
+}
+
+// Authenticates with Password, returns true on Success
+function admin_login($password) {
+    $correct = get_admin_password();
+    if ($correct && $password === $correct) {
+        $_SESSION['is_admin'] = true;
+        return true;
+    }
+    return false;
+}
+
+// Logs out Admin Session
+function admin_logout() {
+    $_SESSION['is_admin'] = false;
+    session_destroy();
+}
+
+// Redirects to Login if not authenticated
+function require_admin() {
+    if (!is_admin()) {
+        header('Location: admin.php?page=login');
+        exit;
+    }
+}