feat(ack): bind test env to deployer and add regression mode

ACK 0.19.0 hands test-environment deploys to the deployer skill,
documents bug-fix as a first-class scenario, and adds
docs/ack/regression.yaml harvest plus a /ack regression run.

skills/ack/examples/regression.example.yaml

@@ -0,0 +1,39 @@
+version: 1
+updatedAt: "2026-08-25T10:00:00+08:00"
+project:
+  name: "notes-web"
+cases:
+  - id: REG-login-001
+    title: 登录后进入工作台
+    status: active
+    source:
+      taskId: BUG-001
+      kind: bug
+    suite: smoke
+    surface: browser
+    setup: 使用测试账号 A，未登录
+    steps:
+      - 打开 /login
+      - 输入账号 A 并提交
+    expected:
+      - kind: visible-text
+        value: 工作台
+      - kind: url
+        value: /dashboard
+  - id: REG-notes-create-001
+    title: 创建笔记后列表出现标题
+    status: active
+    source:
+      taskId: FEAT-012
+      kind: feature
+    suite: full
+    surface: api
+    setup: 已登录账号 A，笔记列表为空
+    steps:
+      - POST /api/notes 创建标题为回归笔记的条目
+      - GET /api/notes
+    expected:
+      - kind: api-status
+        value: "200"
+      - kind: api-field
+        value: "items[].title=回归笔记"