fix(astro): add Astro v6 compatibility (#4135)

* fix(astro): add Astro v6 compatibility

Update peer dependency to accept Astro v6 and bump dev dependency
to astro ^6.0.0.

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

* chore(astro): update devDependencies for post-v1 compatibility

Update vite to ^7.3.1, vitest to ^4.1.1, and astro to ^6.0.8
to align with Astro v6's requirement for Vite 7.

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

---------

Co-authored-by: Claude Opus 4.6 <noreply@anthropic.com>

packages/astro/package.json

@@ -57,10 +57,11 @@
     "linkedom": "^0.18.5",
     "prettier": "^3.4.2",
     "typescript": "^5.8.3",
-    "vite": "^6.3.6",
-    "astro": "^5.16.0"
+    "vite": "^7.3.1",
+    "vitest": "^4.1.1",
+    "astro": "^6.0.8"
   },
   "peerDependencies": {
-    "astro": "^4 || ^5"
+    "astro": "^4 || ^5 || ^6"
   }
 }