fix: split into push-seed step and deploy step per separate when filters

.woodpecker/deploy.yaml

@@ -1,8 +1,16 @@
 steps:
+  - name: seed-push-build
+    image: alpine:3.20
+    commands:
+      - echo "No-op push build."
+      - echo "Exists only so woodpeckerci/plugin-trigger's last-successful"
+      - echo "lookup (which only matches push-event builds) has a build to find."
+    when:
+      event: push
+
   - name: show-deployment-request
     image: alpine:3.20
     commands:
-      - 'echo "Deployment requested:"'
       - 'echo "  ARTIFACT=$ARTIFACT"'
       - 'echo "  TARGET=$TARGET"'
       - test -n "$ARTIFACT" || (echo "ERROR - ARTIFACT param missing" && exit 1)
@@ -10,6 +18,8 @@ steps:
       - test -f "hosts/$TARGET" || (echo "ERROR - unknown host alias $TARGET" && exit 1)
       - 'echo "Resolved host alias $TARGET:"'
       - cat "hosts/$TARGET"
-
     when:
       event: [deployment, manual]
+
+when:
+  event: [deployment, manual, push]