feat: P1-21 ADR 变更级联失效 — 架构变更自动失效已完成任务

- TaskNode 新增 adr_refs 字段（ADR→任务溯源链）
- 新增 INVALIDATED 状态，允许覆盖 DONE/DISPATCHED
- TaskGraph.invalidate_by_adr() 级联失效 + BFS 下游传播
- PlanDelta 新增 rollback_ref（回滚快照引用）
- CascadeReport 数据结构（失效统计 + 任务ID列表）
- Eng dispatch_frozen 冻结调度，ready_tasks() 返回空
- handle_adr_invalidation() 10步处理流程（含 git revert）
- unfreeze_after_replan() Arc 重新规划后解冻
- AirRvr check_invalidated_cleanup() 检查旧代码残留
- INV-15 + L1 保障项 15 写入 SKILL.md
- 11 项功能测试全通过，含 ffmpeg→gstreamer 完整场景

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

lib/air_runtime/review_runtime.py

@@ -136,6 +136,25 @@ class ReviewRuntime:
             "deliveryVerdict": report.get("highRiskAudit", {}).get("deliveryVerdict", "safe-to-ship"),  # P1-19.2
         }
 
+    def check_invalidated_cleanup(self, invalidated_task_ids: list[str]) -> dict:
+        """P1-21: 检查 INVALIDATED 任务的代码是否已清理（无残留）。"""
+        from air_runtime.io import safe_json_load
+        residual = []
+        for tid in invalidated_task_ids:
+            # 检查是否有残留的 result 文件（说明旧代码未被 revert）
+            result_dir = self._state_dir.parent / "airdo" / "tasks" / tid
+            if result_dir.exists():
+                result_file = result_dir / "result.json"
+                if result_file.exists():
+                    data = safe_json_load(result_file)
+                    if data and data.get("status") == "done":
+                        residual.append({"taskId": tid, "reason": "done result still exists — code may not be reverted"})
+        return {
+            "cleaned": len(residual) == 0,
+            "residualCount": len(residual),
+            "residualDetails": residual,
+        }
+
     @staticmethod
     def _report_to_dict(report: ReviewReport) -> dict:
         # P1-19.2: highRiskAudit 序列化