test(course-package): add teacher UI test verifying nav link and page render

Navigate to teacher.moicen.com, verify "课包" nav link is visible for
teacher/supervisor, click through to /course-packages, assert seeded
data renders. Catches frontend build/deploy regressions.

Co-Authored-By: Claude Opus 4.7 <noreply@anthropic.com>

.env.e2e.example

@@ -9,6 +9,8 @@ MOICEN_ADMIN_PASSWORD=
 
 # 课包（course_package）测试依赖 MOICEN_E2E_UNIONID（共用 teacher/student unionid）
 # 测试通过 JWT roles 验证只有 TEACHER/SUPERVISOR 角色可访问课包 API。
+# 教师端 UI 测试需要教师应用基址（默认 https://teacher.moicen.com）
+HTYTEACHER_BASE_URL=https://teacher.moicen.com
 
 # 可选：任意 HTTP 200 健康检查 URL（CI 可在仓库 Settings → Variables 配置 MOICEN_HEALTHCHECK_URL）
 MOICEN_HEALTHCHECK_URL=