feat: rename skills/skiff to pouch and move ACK state under .pouch

Use ~/.pouch, the pouch CLI, and .pouch.yaml as the SSOT container.
Keep the inner skills/ packages, and store ACK project state in
.pouch/ack instead of docs/ack.

tests/test_project_skill.py

@@ -8,18 +8,18 @@ REPO_ROOT = Path(__file__).resolve().parents[1]
 
 
 class ProjectSkillContentTests(unittest.TestCase):
-    def test_skiff_skill_documents_project_usage_and_feedback_loop(self) -> None:
-        content = (REPO_ROOT / "skills" / "skiff" / "SKILL.md").read_text(encoding="utf-8")
+    def test_pouch_skill_documents_project_usage_and_feedback_loop(self) -> None:
+        content = (REPO_ROOT / "skills" / "pouch" / "SKILL.md").read_text(encoding="utf-8")
 
         for expected in (
-            "skiff add <name>",
+            "pouch add <name>",
             "问题或优化回流",
             "实际结果",
             "期望结果",
-            "skiff check <name>",
-            "~/.skills/skills/<name>/",
+            "pouch check <name>",
+            "~/.pouch/skills/<name>/",
             "第三方 skill",
-            "skiff init ack",
+            "pouch init ack",
             "显式调用全局 `/ack` skill",
         ):
             self.assertIn(expected, content)