feat(xl-vask): TRU-71 replace 'Stripe' wording in invoice email (#399)

Implements **TRU-71 (DRIFT 10)** for the api repo: rewrites the
customer-facing Stripe invoice email body so it no longer exposes the
payment-processor name 'Stripe' to the customer. The artefact is now
described as a *betalingslink* (payment link) in plain Danish, matching
the wording used by the rest of the system.

## Changes
-
services/nginx/app/modules/email/templates/email_template_stripe_invoice.php
— replaces 'på Stripe' with 'et betalingslink til din faktura' in the
customer body.
- services/nginx/app/tests/auth/StripeInvoiceEmailTemplateTest.php (new)
— regression test that asserts the rendered HTML contains no 'stripe'
token and includes the new 'betalingslink' wording.

## Tests
- php8.4
services/nginx/app/tests/auth/StripeInvoiceEmailTemplateTest.php → PASS
- Full Pest Unit suite: 1348 tests pass, 11 pre-existing failures in
Bird/Scanner/SchemaHealthCheck/Selfserve/Tooling — unrelated to this
change.

Refs: TRU-71. Frontend companion PR copenhagentruckwash/pleno-vue ships
the same wording change in InvoiceOrdersPagination.vue.

---------

Co-authored-by: perf-investigator <[email protected]>

services/nginx/app/modules/email/templates/email_template_stripe_invoice.php

@@ -32,7 +32,7 @@ class email_template_stripe_invoice
 
         <!-- Email template -->
         <p>Kære <?= $this->name ?>,</p>
-        <p>Tak for din bestilling hos Truck Wash. Vi har sendt dig en faktura på Stripe.
+        <p>Tak for din bestilling hos Truck Wash. Vi har sendt dig et betalingslink til din faktura.
             Du kan betale fakturaen ved at klikke på linket nedenfor:</p>
         <p><a href="<?= $this->stripe_payment_link ?>">Betal faktura for ordre <?= $this->order_id ?></a></p>
         <!-- End of the email template -->

services/nginx/app/tests/Support/legacy_test_manifest.php

@@ -6,6 +6,7 @@ return [
     ['path' => 'tests/auth/PasskeyChallengeTest.php', 'classification' => 'unit', 'type' => 'script'],
     ['path' => 'tests/auth/PemToCoseConversionTest.php', 'classification' => 'unit', 'type' => 'script'],
     ['path' => 'tests/auth/RegisterCvrTest.php', 'classification' => 'unit', 'type' => 'script'],
+    ['path' => 'tests/auth/StripeInvoiceEmailTemplateTest.php', 'classification' => 'unit', 'type' => 'script'],
     ['path' => 'tests/auth/TwoFactorAuthTest.php', 'classification' => 'integration', 'type' => 'script'],
     ['path' => 'tests/auth/WebAuthnInstallTest.php', 'classification' => 'unit', 'type' => 'script'],
     ['path' => 'tests/bookingModule/BookingModuleTest.php', 'classification' => 'unit', 'type' => 'script'],

services/nginx/app/tests/auth/StripeInvoiceEmailTemplateTest.php

@@ -0,0 +1,73 @@
+<?php
+namespace {
+    if (!defined('WD')) {
+        define('WD', dirname(__DIR__, 2));
+    }
+}
+
+namespace {
+    require_once WD . '/modules/email/helpers/email_template.php';
+    require_once WD . '/modules/email/templates/email_template_stripe_invoice.php';
+
+    function assert_true(bool $condition, string $message): void
+    {
+        if (!$condition) {
+            throw new \RuntimeException($message);
+        }
+    }
+
+    function cleanup_buffers_to(int $base_level): string
+    {
+        $output = '';
+        while (ob_get_level() > $base_level) {
+            $output .= (string)ob_get_clean();
+        }
+
+        return $output;
+    }
+
+    $base_level = ob_get_level();
+    ob_start();
+
+    try {
+        $html = (new \email\templates\email_template_stripe_invoice(
+            4242,
+            'https://pay.example.com/invoice/abc',
+            'Anders And'
+        ))->generate_html();
+        $leaked_output = cleanup_buffers_to($base_level);
+
+        assert_true($leaked_output === '', 'Template generation must not leak buffered HTML output.');
+
+        // TRU-71: user-facing wording must not mention the payment processor
+        // by name. The email body must describe the artefact in plain
+        // language instead.
+        assert_true(
+            stripos($html, 'stripe') === false,
+            'Stripe-invoice email body must no longer expose the payment processor name "Stripe" to the customer.'
+        );
+
+        assert_true(
+            str_contains($html, 'betalingslink'),
+            'Stripe-invoice email body must describe the artefact as a betalingslink (payment link).'
+        );
+
+        assert_true(
+            str_contains($html, 'Kære Anders And'),
+            'Template must still greet the customer by name.'
+        );
+
+        assert_true(
+            str_contains($html, 'Betal faktura for ordre 4242'),
+            'Template must still expose a pay-now action link for the order.'
+        );
+    } catch (\Throwable $exception) {
+        $leaked_output = cleanup_buffers_to($base_level);
+        fwrite(STDERR, $leaked_output);
+        fwrite(STDERR, $exception->getMessage() . PHP_EOL);
+        exit(1);
+    }
+
+    echo "\033[32m[PASS]\033[0m Stripe-invoice email template no longer mentions Stripe to the customer.\n";
+    exit(0);
+}