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>

lib/air_runtime/modes/xdb_mode.py

@@ -0,0 +1,44 @@
+"""AirXDB mode -- GUI verification via screenshot capture."""
+
+from __future__ import annotations
+
+from pathlib import Path
+
+from air_runtime.xdb_capture import CaptureManager, CaptureResult
+from air_runtime.events import EventLog, XDB_CAPTURED
+from air_runtime.paths import event_log_path
+
+
+def capture_screenshot(
+    project_root: Path,
+    output_name: str = "screenshot.png",
+    prefer: str = "auto",
+) -> CaptureResult:
+    out_path = project_root / "AirPlan" / "state" / "airxdb" / "captures" / output_name
+    out_path.parent.mkdir(parents=True, exist_ok=True)
+    mgr = CaptureManager()
+    result = mgr.capture(out_path, prefer)
+
+    log = EventLog(event_log_path(project_root))
+    log.emit(XDB_CAPTURED, {
+        "outputName": output_name,
+        "success": result.success,
+        "method": result.method,
+        "outputPath": str(result.output_path),
+    })
+
+    return result
+
+
+def main(args) -> None:
+    project_root = Path(args.project).expanduser().resolve()
+    prefer = getattr(args, "prefer", "auto")
+    output = getattr(args, "output", None) or "screenshot.png"
+
+    result = capture_screenshot(project_root, output, prefer)
+    print("airplan_mode=xdb")
+    print(f"success={result.success}")
+    print(f"method={result.method}")
+    print(f"output={result.output_path}")
+    if result.error:
+        print(f"error={result.error}")