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/app/Jobs/SendTransactionalEmail.php

@@ -0,0 +1,83 @@
+<?php
+
+declare(strict_types=1);
+
+namespace App\Jobs;
+
+use App\Enums\EmailLogStatus;
+use App\Enums\EmailTemplateType;
+use App\Mail\TransactionalMail;
+use App\Models\EmailLog;
+use Illuminate\Bus\Queueable;
+use Illuminate\Contracts\Queue\ShouldQueue;
+use Illuminate\Foundation\Bus\Dispatchable;
+use Illuminate\Queue\InteractsWithQueue;
+use Illuminate\Queue\SerializesModels;
+use Illuminate\Support\Facades\Mail;
+use Illuminate\Support\Str;
+
+final class SendTransactionalEmail implements ShouldQueue
+{
+    use Dispatchable;
+    use InteractsWithQueue;
+    use Queueable;
+    use SerializesModels;
+
+    public int $tries = 3;
+
+    /** @var list<int> */
+    public array $backoff = [30, 120, 300];
+
+    public function __construct(
+        public readonly string $emailLogId,
+        public readonly EmailTemplateType $type,
+        public readonly string $recipientEmail,
+        public readonly string $recipientName,
+        public readonly array $template,
+        public readonly array $branding,
+        public readonly ?string $actionUrl = null,
+    ) {
+        $this->onQueue('emails');
+    }
+
+    public function handle(): void
+    {
+        $emailLog = EmailLog::find($this->emailLogId);
+
+        // Idempotency: don't re-send if already sent or missing
+        if (! $emailLog || $emailLog->status === EmailLogStatus::SENT) {
+            return;
+        }
+
+        try {
+            $mailable = new TransactionalMail(
+                template: $this->template,
+                branding: $this->branding,
+                actionUrl: $this->actionUrl,
+            );
+
+            if ($this->branding['reply_to_email']) {
+                $mailable->replyTo(
+                    $this->branding['reply_to_email'],
+                    $this->branding['reply_to_name'],
+                );
+            }
+
+            Mail::to($this->recipientEmail, $this->recipientName)
+                ->send($mailable);
+
+            $emailLog->update([
+                'status' => EmailLogStatus::SENT->value,
+                'sent_at' => now(),
+            ]);
+        } catch (\Exception $e) {
+            $emailLog->update([
+                'status' => EmailLogStatus::FAILED->value,
+                'failed_at' => now(),
+                'error_message' => Str::limit($e->getMessage(), 500),
+            ]);
+
+            throw $e;
+        }
+    }
+}