fix(deps): update dependency astro to v6

Author: renovate[bot]

apps/docs/package.json

@@ -12,7 +12,7 @@
   "dependencies": {
     "@astrojs/starlight": "^0.37.1",
     "@openscript-ch/starlight-theme": "^0.1.32",
-    "astro": "^5.16.5",
+    "astro": "^6.0.0",
     "sharp": "^0.34.5"
   },
   "packageManager": "pnpm@10.32.1"