feat: rename bugfix-ship/requirement-flow to short-ship/long-ship with shared ship records

short-ship and long-ship share one ship-id record under .pouch/ship/<id>/.
specifier writes PRDs into spec/; delivery-loop appends evidence pointers.
Old names stay as deprecation stubs so existing installs keep working.

skills/ack/references/kickoff.md

@@ -4,6 +4,9 @@
 用户确认后的三角色闭环、飞书收件、启动 worker、交付和回归由 `SKILL.md` 按条件加载，
 不要在本文件开头预读其它规范。
 
+复杂需求的规格和任务写在 `.pouch/ship/<ship-id>/`（specifier + long-ship）。ACK 任务板
+只收缺陷。显式 `/ack` 做功能需求时也先建 ship 记录，不要把功能任务写成 `type: bug`。
+
 ---
 
 ## 前提：谁是 Coordinator