refactor(代码重复): 抽取共享工具函数与 UI 组件，消除多处重复实现

Co-authored-by: Cursor <cursoragent@cursor.com>

src/lib/generators/__tests__/random.test.ts

@@ -0,0 +1,22 @@
+import { randomInt, randomPick } from '@/lib/generators/random';
+
+describe('generators/random', () => {
+  it('randomInt 应返回闭区间内的整数', () => {
+    vi.spyOn(Math, 'random').mockReturnValue(0.5);
+
+    expect(randomInt(1, 10)).toBe(6);
+    expect(randomInt(5, 5)).toBe(5);
+  });
+
+  it('randomPick 应对单元素数组返回该元素', () => {
+    vi.spyOn(Math, 'random').mockReturnValue(0);
+
+    expect(randomPick(['only'])).toBe('only');
+  });
+
+  it('randomPick 应返回数组中的元素', () => {
+    vi.spyOn(Math, 'random').mockReturnValue(0.99);
+
+    expect(randomPick(['a', 'b', 'c'])).toBe('c');
+  });
+});