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/validate_worker_command.py

@@ -13,7 +13,7 @@ import sys
 
 MIGRATION_MESSAGE = (
     "ACK v0.10 已停用自由 worker command 校验器；请在 "
-    "docs/ack/tasks.yaml 的 project.orchestration 中声明 profile，并仅调用 "
+    ".pouch/ack/tasks.yaml 的 project.orchestration 中声明 profile，并仅调用 "
     "scripts/launch_worker.py profile-hash|plan|launch。"
 )