feat(build): integrate generation of manifest file in build process

build/env.ts

@@ -0,0 +1,22 @@
+import { z } from "zod";
+import { configDotenv } from "dotenv";
+
+configDotenv();
+
+const schema = z.object({
+  GITHUB_PAT: z.string().min(1),
+  GITHUB_USERNAME: z.string().min(1),
+});
+
+const result = schema.safeParse(process.env);
+if (result.success === false) {
+  console.error("❌ Invalid environment variables");
+  console.error(
+    result.error.errors
+      .map((error) => `- ${error.path.join(".")}: ${error.message}`)
+      .join("\n"),
+  );
+  process.exit(1);
+}
+
+export const env = result.data;