feat: complete email infrastructure with queue, templates, logging, and API

Adds the full transactional email system:
- Redis queue (QUEUE_CONNECTION=redis), SES config in .env.example
- 3 migrations: organisation_email_settings, organisation_email_templates, email_logs
- EmailTemplateType and EmailLogStatus enums with Dutch defaults
- EmailService as central entry point for all email sending
- SendTransactionalEmail queued job with retries and idempotency
- TransactionalMail mailable with responsive HTML + plain text templates
- Organisation-level branding (colors, logo, footer, reply-to)
- Per-type template overrides with {variable} substitution
- Email log with filtering by status, type, date range, recipient
- Preview and send-test endpoints for template management
- API endpoints: email-settings, email-templates (CRUD), email-logs (read-only)
- Integrated into existing flows: invitations, password reset, email
  verification, registration approval/rejection
- 37 new tests across 4 test files, all existing tests updated

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

api/database/factories/OrganisationEmailSettingsFactory.php

@@ -0,0 +1,28 @@
+<?php
+
+declare(strict_types=1);
+
+namespace Database\Factories;
+
+use App\Models\Organisation;
+use App\Models\OrganisationEmailSettings;
+use Illuminate\Database\Eloquent\Factories\Factory;
+
+/** @extends Factory<OrganisationEmailSettings> */
+final class OrganisationEmailSettingsFactory extends Factory
+{
+    protected $model = OrganisationEmailSettings::class;
+
+    public function definition(): array
+    {
+        return [
+            'organisation_id' => Organisation::factory(),
+            'logo_url' => fake()->optional()->imageUrl(200, 60),
+            'primary_color' => fake()->hexColor(),
+            'secondary_color' => fake()->hexColor(),
+            'footer_text' => '© ' . date('Y') . ' ' . fake()->company(),
+            'reply_to_email' => fake()->optional()->safeEmail(),
+            'reply_to_name' => fake()->optional()->name(),
+        ];
+    }
+}