fix(frontend): 修复前端审计问题并补充回归测试

frontend/src/router/__tests__/title.spec.ts

@@ -0,0 +1,25 @@
+import { describe, expect, it } from 'vitest'
+import { resolveDocumentTitle } from '@/router/title'
+
+describe('resolveDocumentTitle', () => {
+  it('路由存在标题时，使用“路由标题 - 站点名”格式', () => {
+    expect(resolveDocumentTitle('Usage Records', 'My Site')).toBe('Usage Records - My Site')
+  })
+
+  it('路由无标题时，回退到站点名', () => {
+    expect(resolveDocumentTitle(undefined, 'My Site')).toBe('My Site')
+  })
+
+  it('站点名为空时，回退默认站点名', () => {
+    expect(resolveDocumentTitle('Dashboard', '')).toBe('Dashboard - Sub2API')
+    expect(resolveDocumentTitle(undefined, '   ')).toBe('Sub2API')
+  })
+
+  it('站点名变更时仅影响后续路由标题计算', () => {
+    const before = resolveDocumentTitle('Admin Dashboard', 'Alpha')
+    const after = resolveDocumentTitle('Admin Dashboard', 'Beta')
+
+    expect(before).toBe('Admin Dashboard - Alpha')
+    expect(after).toBe('Admin Dashboard - Beta')
+  })
+})