E-Mail-Retry, Voucher-Resend, Tageslimit, Docker-Politur

- Mailer::send mit Retry (2 Versuche); SMTP-Test & Templates waren bereits da
- admin/vouchers.php: Code per E-Mail (erneut) versenden (ajax_resend)
- Tageslimit Voucher pro Nicht-Admin-Benutzer (Setting + Durchsetzung in index)
- Docker: HEALTHCHECK (health.php) + curl; GHCR-Publish-Workflow
- Setting user_daily_voucher_limit + enforce in integrations.php

tests/CryptoTest.php

@@ -0,0 +1,39 @@
+<?php
+namespace Tests;
+
+use PHPUnit\Framework\TestCase;
+
+if (!defined('APP_KEY')) {
+    define('APP_KEY', base64_encode(random_bytes(32)));
+}
+require_once __DIR__ . '/../includes/Crypto.php';
+
+final class CryptoTest extends TestCase
+{
+    public function testRoundtrip(): void
+    {
+        $plain = 'geheim;mit"sonder@zeichen';
+        $cipher = \Crypto::encrypt($plain);
+        $this->assertNotSame($plain, $cipher);
+        $this->assertTrue(\Crypto::isEncrypted($cipher));
+        $this->assertSame($plain, \Crypto::decrypt($cipher));
+    }
+
+    public function testPlaintextPassthrough(): void
+    {
+        // Legacy-/Klartextwerte werden unverändert zurückgegeben.
+        $this->assertSame('altesKlartextPW', \Crypto::decrypt('altesKlartextPW'));
+    }
+
+    public function testEmptyValues(): void
+    {
+        $this->assertSame('', \Crypto::encrypt(''));
+        $this->assertNull(\Crypto::decrypt(null));
+    }
+
+    public function testGenerateKeyLength(): void
+    {
+        $key = \Crypto::generateKey();
+        $this->assertSame(32, strlen(base64_decode($key)));
+    }
+}