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/tenancy/static/admin/js/platform-menu-config.js

@@ -1,8 +1,7 @@
 // static/admin/js/platform-menu-config.js
 // Platform menu configuration management
 //
-// TODO: BUG - Sidebar menu doesn't update immediately after changes.
-// See my-menu-config.js for details and possible solutions.
+// Sidebar updates correctly here via window.location.reload() after changes.
 
 const menuConfigLog = window.LogConfig?.loggers?.menuConfig || window.LogConfig?.createLogger?.('menuConfig') || console;