feat: software-engineering skill v0.3 (P1-1..P1-4 + P2)

- P1-1 directory-isolation executable check: git diff --name-only
  against merge-base, output recorded in merge record
- P1-2 derivation checklist table (8 required items, missing one blocks dispatch)
- P1-3 QA split into single-client review and cross-client E2E with
  fixed deliverables and agent-test attribution
- P1-4 sub-task slim-pack trimming rules (listed chapters only, never full copies)
- P2: inter-thread Q&A default policy, docs/decisions.md append-only,
  per-client onboarding docs (web first at G4a), v1.1 handover checklist
- Body and appendix kept in sync; new lightweight keyword test

cloud/tests/test_software_engineering_v03.py

@@ -0,0 +1,44 @@
+"""software-engineering 技能 v0.3：P1/P2 关键词断言（轻量）。
+
+只断言正文与附录都含有 v0.3 的关键概念，不逐字背诵全文：
+版本号与上一版、目录隔离可执行检查、派生必填表、精简包所含章节、
+QA 两部分交付物与 agent 测试归属、决策记录落盘与只追加、
+上手文档与 v1.1 交接清单。正文改了附录没同步时，附录部分就会失败。
+"""
+
+import unittest
+from pathlib import Path
+
+SKILL = Path(__file__).resolve().parents[1] / "skills" / "software-engineering" / "SKILL.md"
+
+# 正文与附录都要有的关键词
+BOTH = ("v0.3", "git diff --name-only", "精简包", "所含章节",
+        "单端复核", "跨端一致性矩阵", "沙箱越界", "模型 503",
+        "docs/decisions.md", "只追加", "上手文档", "v1.1 交接清单")
+
+# 派生必填表 8 项：正文表格与协调员附录都要出现
+CHECKLIST = ("客户端名", "拥有目录", "分支名", "契约版本",
+             "PRD 版本", "设计版本", "完成定义", "TODO-UPDATE")
+
+
+class SoftwareEngineeringV03TestCase(unittest.TestCase):
+    def test_v03_in_body_and_appendix(self):
+        text = SKILL.read_text(encoding="utf-8")
+        main, sep, appendix = text.partition("## 附录：角色模板")
+        self.assertTrue(sep, "appendix marker missing")
+        self.assertIn("v0.2", main, "header must name the previous version")
+        self.assertIn("GitHub 保证", main, "header must name the previous GitHub guarantees")
+        for kw in BOTH:
+            self.assertIn(kw, main, kw)
+            self.assertIn(kw, appendix, "appendix: " + kw)
+        for kw in CHECKLIST:
+            self.assertIn(kw, main, kw)
+            self.assertIn(kw, appendix, "appendix: " + kw)
+
+    def test_v03_no_full_copy_rule(self):
+        text = SKILL.read_text(encoding="utf-8")
+        self.assertIn("绝不把 PRD、契约", text)
+
+
+if __name__ == "__main__":
+    unittest.main()