feat: MyEasyCMS v2 — Full SaaS rebuild

Complete rebuild of 22-year-old PHP CMS as modern SaaS:

Database (15 migrations, 42+ tables):
- Foundation: account_settings, audit_log, GDPR register, cms_files
- Module Engine: modules, fields, records, permissions, relations + RPC
- Members: 45+ field member profiles, departments, roles, honors, SEPA mandates
- Courses: courses, sessions, categories, instructors, locations, attendance
- Bookings: rooms, guests, bookings with availability
- Events: events, registrations, holiday passes
- Finance: SEPA batches/items (pain.008/001 XML), invoices
- Newsletter: campaigns, templates, recipients, subscriptions
- Site Builder: site_pages (Puck JSON), site_settings, cms_posts
- Portal Auth: member_portal_invitations, user linking

Feature Packages (9):
- @kit/module-builder — dynamic low-code CRUD engine
- @kit/member-management — 31 API methods, 21 actions, 8 components
- @kit/course-management, @kit/booking-management, @kit/event-management
- @kit/finance — SEPA XML generator + IBAN validator
- @kit/newsletter — campaigns + dispatch
- @kit/document-generator — PDF/Excel/Word
- @kit/site-builder — Puck visual editor, 15 blocks, public rendering

Pages (60+):
- Dashboard with real stats from all APIs
- Full CRUD for all 8 domains with react-hook-form + Zod
- Recharts statistics
- German i18n throughout
- Member portal with auth + invitation system
- Public club websites via Puck at /club/[slug]

Infrastructure:
- Dockerfile (multi-stage, standalone output)
- docker-compose.yml (Supabase self-hosted + Next.js)
- Kong API gateway config
- .env.production.example

apps/web/i18n/messages/de/common.json

@@ -74,7 +74,8 @@
     "finance": "Finanzen",
     "documents": "Dokumente",
     "newsletter": "Newsletter",
-    "events": "Veranstaltungen"
+    "events": "Veranstaltungen",
+    "siteBuilder": "Website"
   },
   "roles": {
     "owner": {