feat: production launch — email audit, team invites, security headers, router fixes

- Fix loyalty & monitoring router bugs (_get_router → named routers)
- Implement team invitation email with send_template + seed templates (en/fr/de)
- Add SecurityHeadersMiddleware (nosniff, HSTS, referrer-policy, permissions-policy)
- Build email audit admin page: service, schemas, API, page route, menu, i18n, HTML, JS
- Clean stale TODO in platform-menu-config.js
- Add 67 tests (unit + integration) covering all new functionality

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

app/modules/messaging/definition.py

@@ -79,6 +79,7 @@ messaging_module = ModuleDefinition(
         FrontendType.ADMIN: [
             "messages",  # Admin messages
             "notifications",  # Admin notifications
+            "email-logs",  # Email audit logs
         ],
         FrontendType.STORE: [
             "messages",  # Store messages
@@ -116,6 +117,13 @@ messaging_module = ModuleDefinition(
                         route="/admin/notifications",
                         order=40,
                     ),
+                    MenuItemDefinition(
+                        id="email-logs",
+                        label_key="messaging.menu.email_logs",
+                        icon="envelope",
+                        route="/admin/email-logs",
+                        order=50,
+                    ),
                 ],
             ),
             MenuSectionDefinition(