feat: Astro Starlight Docs-Site für BTC MAIN AI Application Layer

Vollständige Dokumentations-Site mit:
- Einstieg: Einführung, Schnellstart, Kernkonzepte
- Guides: Deployment, CI/CD, Env-Vars, Domains, Logs
- API-Referenz: Überblick, Auth, Applications, Deployments
- Referenz: Tech Stack, FAQ
- Dockerfile + nginx für containerisiertes Deployment

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

package.json

@@ -0,0 +1,17 @@
+{
+  "name": "btc-main-ai-docs",
+  "type": "module",
+  "version": "1.0.0",
+  "scripts": {
+    "dev": "astro dev",
+    "start": "astro dev",
+    "build": "astro build",
+    "preview": "astro preview",
+    "astro": "astro"
+  },
+  "dependencies": {
+    "@astrojs/starlight": "^0.32.0",
+    "astro": "^5.0.0",
+    "sharp": "^0.33.0"
+  }
+}