Add contact page with form, email template, and tests

- Create ContactController with GET/POST handling and MailerService integration
- Create contact page template with name, surname, email, message form
- Create dedicated email template for contact messages
- Update navbar links (desktop + mobile) to point to /contact route
- Add ContactControllerTest with 5 tests covering form submission and validation

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

tests/Controller/ContactControllerTest.php

@@ -0,0 +1,76 @@
+<?php
+
+namespace App\Tests\Controller;
+
+use App\Service\MailerService;
+use Symfony\Bundle\FrameworkBundle\Test\WebTestCase;
+
+class ContactControllerTest extends WebTestCase
+{
+    public function testContactPageReturnsSuccess(): void
+    {
+        $client = static::createClient();
+        $client->request('GET', '/contact');
+
+        self::assertResponseIsSuccessful();
+    }
+
+    public function testContactFormSubmitRedirectsWithSuccess(): void
+    {
+        $client = static::createClient();
+
+        $mailer = $this->createMock(MailerService::class);
+        $mailer->expects(self::once())->method('sendEmail');
+        static::getContainer()->set(MailerService::class, $mailer);
+
+        $client->request('POST', '/contact', [
+            'name' => 'Dupont',
+            'surname' => 'Jean',
+            'email' => 'jean@exemple.fr',
+            'message' => 'Bonjour, je voudrais des informations.',
+        ]);
+
+        self::assertResponseRedirects('/contact');
+        $client->followRedirect();
+        self::assertSelectorExists('.font-black.text-sm');
+    }
+
+    public function testContactFormEmptyFieldsRedirectsWithError(): void
+    {
+        $client = static::createClient();
+        $client->request('POST', '/contact', [
+            'name' => '',
+            'surname' => 'Jean',
+            'email' => 'jean@exemple.fr',
+            'message' => 'Bonjour',
+        ]);
+
+        self::assertResponseRedirects('/contact');
+    }
+
+    public function testContactFormAllEmptyRedirectsWithError(): void
+    {
+        $client = static::createClient();
+        $client->request('POST', '/contact', [
+            'name' => '',
+            'surname' => '',
+            'email' => '',
+            'message' => '',
+        ]);
+
+        self::assertResponseRedirects('/contact');
+    }
+
+    public function testContactFormWhitespaceOnlyRedirectsWithError(): void
+    {
+        $client = static::createClient();
+        $client->request('POST', '/contact', [
+            'name' => '   ',
+            'surname' => 'Jean',
+            'email' => 'jean@exemple.fr',
+            'message' => 'Bonjour',
+        ]);
+
+        self::assertResponseRedirects('/contact');
+    }
+}