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/delivery.example.yaml

@@ -7,7 +7,9 @@ enabled: true
 defaultProfile: "review"
 
 intents:
-  testEnvironment: test-env
+  testEnvironment:
+    via: deployer
+    env: test
   release: null
 
 entrypoints:
@@ -104,19 +106,6 @@ environments:
     mutex: "notes-test-deploy"
 
 profiles:
-  test-env:
-    stopAt: validation_ready
-    steps:
-      - id: build-deb
-        action: build
-        artifact: service-deb
-      - id: deploy-test
-        action: deploy
-        artifact: service-deb
-        environment: test-server
-      - id: smoke-test
-        action: health-check
-        environment: test-server
   review:
     stopAt: review_ready
     steps: