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>

dev-docs/API.md

@@ -922,3 +922,121 @@ Base path: `/api/v1/admin/`
 - Impersonation token has name `impersonation-by-{admin_id}`
 - Admin ID is cached for 4 hours at key `impersonation:{token_id}`
 - Activity log records both start (`admin.impersonation.started`) and stop (`admin.impersonation.stopped`)
+
+## Email Settings (org admin)
+
+- `GET /organisations/{org}/email-settings` — get current email branding settings (returns defaults if none configured)
+- `PUT /organisations/{org}/email-settings` — create or update email branding settings
+
+### PUT body
+
+```json
+{
+  "logo_url": "https://example.com/logo.png",
+  "primary_color": "#FF5500",
+  "secondary_color": "#CC4400",
+  "footer_text": "© 2026 Stichting Feestfabriek",
+  "reply_to_email": "info@festival.nl",
+  "reply_to_name": "Festival Team"
+}
+```
+
+All fields are optional/nullable. Colors must match `#[0-9A-Fa-f]{6}`.
+
+## Email Templates (org admin)
+
+- `GET /organisations/{org}/email-templates` — list all template types with current content (custom or default)
+- `GET /organisations/{org}/email-templates/{type}` — get single template with both custom content and defaults
+- `PUT /organisations/{org}/email-templates/{type}` — create or update custom template for this type
+- `DELETE /organisations/{org}/email-templates/{type}` — reset to system default (deletes custom override)
+- `POST /organisations/{org}/email-templates/{type}/preview` — render email HTML with sample data
+- `POST /organisations/{org}/email-templates/{type}/send-test` — send test email. Body: `{ "email": "test@example.com" }`
+
+### Template types
+
+`invitation`, `password_reset`, `email_verification`, `registration_approved`, `registration_rejected`, `shift_assignment`
+
+### PUT body
+
+```json
+{
+  "subject": "Aangepaste uitnodiging voor {organisation_name}",
+  "heading": "Welkom!",
+  "body_text": "Aangepaste tekst met {organisation_name} variabelen.",
+  "button_text": "Klik hier"
+}
+```
+
+### GET response (index)
+
+Returns array of all template types with resolved content:
+
+```json
+{
+  "data": [
+    {
+      "type": "invitation",
+      "label": "Uitnodiging",
+      "is_custom": false,
+      "subject": "Je bent uitgenodigd voor {organisation_name}",
+      "heading": "Welkom bij {organisation_name}!",
+      "body_text": "...",
+      "button_text": "Uitnodiging accepteren",
+      "defaults": { "subject": "...", "heading": "...", "body_text": "...", "button_text": "..." }
+    }
+  ]
+}
+```
+
+### Template variables
+
+- `{organisation_name}` — available in all templates
+- `{event_name}` — available in registration and shift templates
+- `{shift_title}`, `{shift_date}`, `{shift_start}`, `{shift_end}`, `{section_name}` — shift assignment only
+
+## Email Logs (org admin, read-only)
+
+- `GET /organisations/{org}/email-logs` — paginated email log
+
+### Query parameters
+
+| Param           | Type   | Description                          |
+| --------------- | ------ | ------------------------------------ |
+| `search`        | string | Search by recipient_email            |
+| `status`        | string | Filter: `queued\|sent\|failed`       |
+| `template_type` | string | Filter by EmailTemplateType          |
+| `event_id`      | ULID   | Filter by event                      |
+| `person_id`     | ULID   | Filter by person                     |
+| `from`          | date   | Start of date range                  |
+| `to`            | date   | End of date range                    |
+| `per_page`      | int    | Results per page (default 15)        |
+
+### Response
+
+```json
+{
+  "data": {
+    "data": [
+      {
+        "id": "01JXYZ...",
+        "recipient_email": "volunteer@test.nl",
+        "recipient_name": "Jan Janssen",
+        "template_type": "registration_approved",
+        "template_label": "Registratie goedgekeurd",
+        "subject": "Je registratie voor Festival X is goedgekeurd!",
+        "status": "sent",
+        "error_message": null,
+        "queued_at": "2026-04-15T12:00:00+00:00",
+        "sent_at": "2026-04-15T12:00:05+00:00",
+        "failed_at": null,
+        "triggered_by": { "id": "01JXYZ...", "name": "Admin User" },
+        "event_id": "01JXYZ...",
+        "person_id": "01JXYZ...",
+        "created_at": "2026-04-15T12:00:00+00:00"
+      }
+    ],
+    "links": { "...pagination..." },
+    "meta": { "...pagination..." }
+  }
+}
+```