feat: add MCP server with resources, tools, auth, and Traefik routing

- Add backend/app/mcp_server.py with FastMCP server (hms-cms)
- Resources: design-rules, page-structure, sync-status
- Tools: trigger_sync, get_sync_log, set_rentman_token, read_file,
  write_file, create_page, deploy, git_commit, git_status
- Bearer token auth via MCP_AUTH_TOKEN env var
- Mount MCP at /mcp with streamable HTTP transport
- Integrate session manager in FastAPI lifespan
- Add Traefik labels for external /mcp route on hms.media-on.de
- Add git, docker.io, curl to backend Dockerfile
- Mount repo root + docker socket in backend container
- Add mcp>=1.0.0 to requirements.txt

frontend-nuxt-old/app.vue

@@ -0,0 +1,11 @@
+<template>
+  <div>
+    <NuxtLayout>
+      <NuxtPage />
+    </NuxtLayout>
+  </div>
+</template>
+
+<script setup lang="ts">
+// App root – wraps all pages in default layout
+</script>