Add packageManager field to package.json

Specified pnpm version in the packageManager field to ensure consistent package management across environments.

Author: austin-smith

package.json

@@ -24,5 +24,6 @@
     "eslint-plugin-astro": "^1.3.1",
     "tailwindcss": "^4.1.14",
     "typescript": "^5.9.3"
-  }
-}
+  },
+  "packageManager": "pnpm@10.27.0+sha512.72d699da16b1179c14ba9e64dc71c9a40988cbdc65c264cb0e489db7de917f20dcf4d64d8723625f2969ba52d4b7e2a1170682d9ac2a5dcaeaab732b7e16f04a"
+}