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_ack_skill.py

@@ -13,11 +13,11 @@ class AckSkillContentTests(unittest.TestCase):
         content = (REPO_ROOT / "skills" / "ack" / "SKILL.md").read_text(encoding="utf-8")
 
         for expected in (
-            "skiff init ack --project <project-root>",
-            "docs/ack/project.md",
-            "docs/ack/tasks.yaml",
-            "docs/ack/knowledge.yaml",
-            "docs/ack/delivery.yaml",
+            "pouch init ack --project <project-root>",
+            ".pouch/ack/project.md",
+            ".pouch/ack/tasks.yaml",
+            ".pouch/ack/knowledge.yaml",
+            ".pouch/ack/delivery.yaml",
             "tasks: []",
             "validate_tasks.py",
             "validate_knowledge.py",
@@ -131,7 +131,7 @@ class AckSkillContentTests(unittest.TestCase):
         ):
             self.assertTrue((ack_dir / relative_path).is_file(), relative_path)
         version = (ack_dir / "VERSION").read_text(encoding="utf-8").strip()
-        self.assertEqual(version, "0.18.0")
+        self.assertEqual(version, "0.19.0")
         self.assertIn(
             f'ackVersion: "{version}"',
             (ack_dir / "examples" / "tasks.example.yaml").read_text(encoding="utf-8"),
@@ -156,7 +156,7 @@ class AckSkillContentTests(unittest.TestCase):
         # v0.19 起 allowedWorktrees 白名单废弃：模板只保留废弃说明注释，不再生成该字段
         self.assertNotIn("allowedWorktrees:", template)
         self.assertIn("allowedWorktrees", template)
-        self.assertIn('knowledgeFile: "docs/ack/knowledge.yaml"', template)
+        self.assertIn('knowledgeFile: ".pouch/ack/knowledge.yaml"', template)
 
 
 if __name__ == "__main__":