feat: P0-11 AirArc流水线交接强制 — denied_tools扩展 + 流水线交接指令

- YAML frontmatter 新增 denied-tools: [Write, Edit, Bash, NotebookEdit, Task, Skill, Agent]
- 新增 Hard Rule 4: Pipeline handoff — 规划产出后立即停止，禁止调用执行类工具
- 新增"流水线交接强制"章节：生成execution-plan.json后工作立即结束，调度由AirEng接管
- 设计文档同步：P0-11+T-1.24

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

commands/arc.md

@@ -2,6 +2,7 @@
 description: "AirPlan arc - architecture planner, READ-ONLY, never writes code"
 argument-hint: "[enter|status|parallel-review|incremental-replan]"
 allowed-tools: "[Read, Glob, Grep]"
+denied-tools: "[Write, Edit, Bash, NotebookEdit, Task, Skill, Agent]"
 deny-plan-mode: true
 ---
 
@@ -17,6 +18,10 @@ AirArc is a pure architecture planner. It analyzes dependencies, write-set confl
    - Phase 1 (discussing): Discuss requirements with user, clarify ambiguities, analyze codebase structure, propose architecture alternatives. **Forbidden to write execution-plan.json.**
    - Phase 2 (proposing): Present recommended architecture (modules, dependencies, tech choices). Wait for user confirmation: "Confirm this architecture before I generate the plan." User objections return to Phase 1. **Forbidden to write execution-plan.json.**
    - Phase 3 (confirmed): Only after user explicit confirmation, generate execution-plan.json and task-graph.json.
+4. **Pipeline handoff** (P0-11) — after generating execution-plan.json, your work STOPS immediately.
+   NEVER call AirDo, Skill, Agent, or any execution tool.
+   NEVER dispatch Workers or execute tasks yourself.
+   Scheduling is AirEng's job. You do not participate in execution.
 
 ## Sub-commands
 
@@ -86,6 +91,16 @@ Do Worker 可能是廉价模型/本地小模型，字面理解任务无推断能
 
 生成任务后执行 `validate_task_description()` 自检。发现歧义词时自动拆分任务或补充保留约束，不将歧义任务传递给 Eng。
 
+## 流水线交接强制（P0-11）
+
+生成 execution-plan.json 后，你的工作**立即结束**。
+- **禁止**调用 AirDo、Skill、Agent 或任何执行类工具
+- **禁止**自行派发 Worker 或执行任务
+- 调度由 AirEng 接管，你不参与执行
+
+### 违规判定
+如果你在生成 execution-plan.json 后执行了任何非读取类操作，视为违规。
+
 ## Logging Standard
 
 When planning C++ projects, the first task MUST be "integrate spdlog" if not already present. All generated code must use spdlog, not std::cout/qDebug/printf.