Replace PHP WIP with vanilla version

src/app/public/user/logged-on.php

@@ -0,0 +1,26 @@
+<?php
+declare(strict_types=1);
+
+require_once '../../lib/start.php';
+
+use MyPrayerJournal\Constants;
+
+$auth0->exchange("{$_ENV[Constants::BASE_URL]}/user/logged-on");
+
+$nextUrl = '/journal';
+if (array_key_exists(Constants::LOG_ON_STATE, $_GET)) {
+    $nonce = base64_decode(urldecode($_GET[Constants::LOG_ON_STATE]));
+    [$verify, $newNext] = explode('|', $_COOKIE[Constants::COOKIE_REDIRECT]);
+    if ($verify == $nonce && $newNext && str_starts_with($newNext, '/') && !str_starts_with($newNext, '//')) {
+        $nextUrl = $newNext;
+    }
+}
+
+setcookie(Constants::COOKIE_REDIRECT, '', [
+    'expires'  => -1,
+    'secure'   => true,
+    'httponly' => true,
+    'samesite' => 'Strict'
+]);
+header("Location: $nextUrl");
+exit;