feat: production deployment - full update with providers, admin, glossaries, pricing, tests

Major changes across backend, frontend, infrastructure:
- Provider system with model selection (Google, DeepL, OpenAI, Ollama, Google Cloud)
- Admin panel: user management, pricing, settings
- Glossary system with CSV import/export
- Subscription and tier quota management
- Security hardening (rate limiting, API key auth, path traversal fixes)
- Docker compose for dev, prod, and IONOS deployment
- Alembic migrations for new tables
- Frontend: dashboard, pricing page, landing page, i18n (en/fr)
- Test suite and verification scripts

Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>

office-translator-landing-page/app/admin/layout.tsx

@@ -0,0 +1,14 @@
+import type { Metadata } from "next"
+
+export const metadata: Metadata = {
+  title: "Admin - Office Translator",
+  description: "System administration and user management dashboard.",
+}
+
+export default function AdminLayout({
+  children,
+}: {
+  children: React.ReactNode
+}) {
+  return <>{children}</>
+}