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/error.vue

@@ -0,0 +1,27 @@
+<template>
+  <div class="min-h-screen flex flex-col">
+    <AppHeader />
+    <main id="main-content" class="flex-1" role="main">
+      <div class="max-w-md mx-auto px-4 py-24 text-center">
+        <div class="text-8xl font-bold mb-4" style="color: var(--secondary)">404</div>
+        <h1 class="text-2xl font-semibold mb-2" style="color: var(--text)">Seite nicht gefunden</h1>
+        <p class="mb-8" style="color: var(--secondary)">Die angeforderte Seite existiert nicht.</p>
+        <NuxtLink to="/" class="hms-btn hms-btn-primary">Zur Startseite</NuxtLink>
+      </div>
+    </main>
+    <AppFooter />
+  </div>
+</template>
+
+<script setup lang="ts">
+import type { NuxtError } from "#app";
+
+const props = defineProps<{ error: NuxtError }>();
+
+useHead({
+  title: `${props.error.statusCode} – HMS Licht & Ton`,
+  meta: [
+    { name: "robots", content: "noindex, nofollow, noarchive, nosnippet" },
+  ],
+});
+</script>