feat: P1-19 P1-20 实现 - 边界测试强制 + 高风险审计 + UI Skill 路由

P1-19.1: Arc 边界测试强制
- TaskNode 新增 test_required 字段
- _inject_boundary_tests() 为每个模块注入接口测试和单元测试任务
- Done When 验证必须包含"测试通过"

P1-19.2: AirRvr 高风险审计
- 新增 HighRiskAudit, HighRiskFinding 数据类
- ReviewReport 新增 highRiskAudit 字段，含 lifecycle/nullPointer/danglingPointer/exceptionSafety/concurrency + overallRisk + deliveryVerdict
- 序列化/反序列化支持

P1-19.3: block-release 集成
- dispatch_worker_group() 派发前扫描最新审查报告
- deliveryVerdict=block-release 时阻止所有后续派发
- 记录 eng.blocked 事件

P1-20: frontend-design Skill 集成
- is_ui_task() UI 任务检测
- ensure_frontend_design_skill() 自动安装 Skill
- route_ui_task() UI 任务路由决策
- enter_worker() 集成 UI 检测，skill 不可用时阻止执行
- commands/do.md 更新 UI 处理说明
- SKILL.md 新增 INV-12/INV-13/INV-14

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

SKILL.md

@@ -0,0 +1,10 @@
+---
+name: airplan-v2
+description: TODO — describe WHEN Claude should use this. Include trigger phrases users
+  might say ("do X", "set up Y", "review Z"). Be specific; this string is what Claude
+  matches the user's request against.
+---
+
+# airplan-v2
+
+TODO: what this skill does, and the steps Claude should take.