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.

skills/ack/scripts/run_verification.py

@@ -57,7 +57,7 @@ def _validate_knowledge_location(
     knowledge_path: Path,
     project_root: Path,
 ) -> str | None:
-    expected = project_root / "docs" / "ack" / "knowledge.yaml"
+    expected = project_root / ".pouch" / "ack" / "knowledge.yaml"
     lexical = Path(os.path.abspath(knowledge_path.expanduser()))
     if lexical != expected:
         return (
@@ -171,7 +171,7 @@ def load_authoritative_knowledge(
 ) -> tuple[dict[str, Any] | None, str | None]:
     source_fd, open_error = _open_regular_beneath(
         project_root,
-        "docs/ack/knowledge.yaml",
+        ".pouch/ack/knowledge.yaml",
         require_executable=False,
     )
     if open_error is not None or source_fd is None:
@@ -329,7 +329,7 @@ def main(argv: list[str] | None = None) -> int:
     parser.add_argument("verification_ref", help="verificationRegistry 中的检查 ID")
     parser.add_argument(
         "--project-root",
-        help="项目根目录；默认从 knowledge.yaml 的 docs/ack 布局或 Git 推断",
+        help="项目根目录；默认从 knowledge.yaml 的 .pouch/ack 布局或 Git 推断",
     )
     args = parser.parse_args(argv)