Add core env loader

test/core/config/env.test.ts

@@ -0,0 +1,19 @@
+import { describe, expect, it } from 'vitest';
+import { z } from 'zod';
+import { loadEnv } from '../../../src/core/config/env';
+
+describe('loadEnv', () => {
+  const schema = z.object({
+    FOO: z.string(),
+    COUNT: z.coerce.number().default(5),
+  });
+
+  it('parses matching env vars into a typed object', () => {
+    const result = loadEnv(schema, { FOO: 'bar', COUNT: '10' });
+    expect(result).toEqual({ FOO: 'bar', COUNT: 10 });
+  });
+
+  it('throws a descriptive error when required vars are missing', () => {
+    expect(() => loadEnv(schema, {})).toThrow(/Invalid environment configuration/);
+  });
+});