refactor: use new astro env (#507)

* refactor: use new astro env

* chore: directly use PUBLIC_GOOGLE_SITE_VERIFICATION

astro.config.ts

@@ -1,4 +1,4 @@
-import { defineConfig } from "astro/config";
+import { defineConfig, envField } from "astro/config";
 import tailwindcss from "@tailwindcss/vite";
 import sitemap from "@astrojs/sitemap";
 import remarkToc from "remark-toc";
@@ -32,6 +32,15 @@ export default defineConfig({
     // Used for all `<Image />` and `<Picture />` components unless overridden with a prop
     experimentalLayout: "responsive",
   },
+  env: {
+    schema: {
+      PUBLIC_GOOGLE_SITE_VERIFICATION: envField.string({
+        access: "public",
+        context: "client",
+        optional: true,
+      }),
+    },
+  },
   experimental: {
     svg: true,
     responsiveImages: true,