feat: 3.2.17中途变更处理(git驱动) + 3.2.9a Worker git强制 + 3.2.5 Phase7 squash merge + Arc git初始化检测

- 新增 ChangeClassifier（爆炸半径分类：IMPLEMENTATION/INTERFACE/GLOBAL_CONSTRAINT）
- 新增 ImpactPropagator（BFS影响传播：IMPACTED/BOUNDARY/SAFE差异化标记）
- task_graph.py：invalidate_by_adr()差异化失效 + CascadeReport扩展字段（向后兼容）
- eng_mode.py：三阶段差异化流程（分类→传播→失效→git操作→验证任务→重规划）
- eng_mode.py：_git_squash_merge_and_tag() + Phase 7 集成
- do_mode.py：_ensure_all_committed() Worker git操作强制
- adr_watcher.py：内容快照 + get_content_for_classification()
- events.py：ADR_CLASSIFIED/IMPACT_PROPAGATED/BOUNDARY_VERIFICATION_GENERATED
- partial_replanner.py：replan_with_constraints() + generate_verification_tasks()
- project_bootstrap.py：ensure_git_initialized() Arc规划前检测
- test_p1_21_phase2.py：21个新测试，95个全量测试0失败

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

lib/air_runtime/modes/do_mode.py

@@ -17,6 +17,30 @@ from air_runtime.contracts import WorkerResult, now_iso
 from air_runtime.utils import sanitize_task_id, session_stamp
 
 
+def _ensure_all_committed(project_root: Path, task_id: str) -> None:
+    """3.2.9a: Worker git 操作强制 — 检查所有变更已提交。
+
+    在 Worker finish 前强制检查 git status，未提交的变更阻止完成。
+    确保 Worktree 分支上所有修改都已 git add + git commit。
+    """
+    import subprocess
+    try:
+        r = subprocess.run(
+            ["git", "status", "--porcelain"],
+            cwd=project_root, capture_output=True, text=True, timeout=10,
+        )
+        if r.returncode != 0:
+            return  # git not available, skip check
+        if r.stdout.strip():
+            raise RuntimeError(
+                f"Worker {task_id}: 存在未提交的变更，禁止 finish。\n"
+                f"未提交文件:\n{r.stdout.strip()}\n"
+                f"请先 git add && git commit 后再 finish。"
+            )
+    except FileNotFoundError:
+        pass  # git not available, skip check
+
+
 # GUI 任务检测关键词
 GUI_INDICATORS = {
     "gui", "ui", "render", "layout", "dialog", "osd",
@@ -204,6 +228,9 @@ def finish_worker(project_root: Path, task_id: str, result_path: Path | None = N
     tid = sanitize_task_id(task_id)
     paths = _paths(project_root, tid)
 
+    # 3.2.9a: Worker git 操作强制 — 所有变更必须已提交
+    _ensure_all_committed(project_root, tid)
+
     # 加载 result
     if result_path and result_path.exists():
         result_data = safe_json_load(result_path)