Add core env loader

src/core/config/env.ts

@@ -0,0 +1,9 @@
+import type { ZodSchema } from 'zod';
+
+export function loadEnv<T>(schema: ZodSchema<T>, source: NodeJS.ProcessEnv = process.env): T {
+  const result = schema.safeParse(source);
+  if (!result.success) {
+    throw new Error(`Invalid environment configuration: ${result.error.message}`);
+  }
+  return result.data;
+}