feat: core utilities - CSRF, auth, encryption, PHPMailer

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

includes/mailer.php

@@ -0,0 +1,40 @@
+<?php
+require_once __DIR__ . '/config.php';
+require_once __DIR__ . '/../vendor/phpmailer/PHPMailer.php';
+require_once __DIR__ . '/../vendor/phpmailer/SMTP.php';
+require_once __DIR__ . '/../vendor/phpmailer/Exception.php';
+
+use PHPMailer\PHPMailer\PHPMailer;
+
+function sendEmail(string $subject, string $htmlBody, ?string $toEmail = null): bool {
+    $mail = new PHPMailer(true);
+    try {
+        $mail->isSMTP();
+        $mail->Host = SMTP_HOST;
+        $mail->SMTPAuth = true;
+        $mail->Username = SMTP_USER;
+        $mail->Password = SMTP_PASS;
+        $mail->SMTPSecure = PHPMailer::ENCRYPTION_SMTPS;
+        $mail->Port = SMTP_PORT;
+        $mail->CharSet = 'UTF-8';
+
+        $mail->setFrom(SMTP_USER, SMTP_FROM_NAME);
+        $mail->addAddress($toEmail ?? SMTP_USER);
+
+        $mail->isHTML(true);
+        $mail->Subject = $subject;
+        $mail->Body = $htmlBody;
+        $mail->AltBody = strip_tags($htmlBody);
+
+        $mail->send();
+        return true;
+    } catch (\Exception $e) {
+        error_log('Email error: ' . $e->getMessage());
+        return false;
+    }
+}
+
+function buildWhatsAppLink(string $serviceName, string $clientName, string $phone): string {
+    $message = "Hola, soy *{$clientName}* y estoy interesado/a en el servicio de *{$serviceName}*. Mi teléfono es {$phone}. Acabo de enviar mi solicitud por la página web.";
+    return 'https://wa.me/' . WHATSAPP_NUMBER . '?text=' . urlencode($message);
+}