feat: 新增 news 内容集合与 Zod schema（含单测）

tests/content-schema.test.ts

@@ -0,0 +1,28 @@
+import { describe, it, expect } from 'vitest';
+import { newsSchema } from '../src/content/schemas';
+
+describe('newsSchema', () => {
+  it('accepts valid frontmatter and coerces date', () => {
+    const parsed = newsSchema.parse({
+      title: '官网基座启动',
+      date: '2026-07-23',
+      category: '公告',
+    });
+    expect(parsed.title).toBe('官网基座启动');
+    expect(parsed.date).toEqual(new Date('2026-07-23'));
+    expect(parsed.category).toBe('公告');
+  });
+
+  it('defaults category to 未分类', () => {
+    const parsed = newsSchema.parse({ title: '测试', date: '2026-07-23' });
+    expect(parsed.category).toBe('未分类');
+  });
+
+  it('rejects missing title', () => {
+    expect(() => newsSchema.parse({ date: '2026-07-23' })).toThrow();
+  });
+
+  it('rejects missing date', () => {
+    expect(() => newsSchema.parse({ title: '测试' })).toThrow();
+  });
+});