fix: skip retiring images still in use by app containers

When ps:rebuild runs against an image-based deploy via git:from-image, the resulting image often shares the same SHA as the previous deployment, so retiring the old container's image would target the live image of the new container. The retirement is now skipped when another running container of the same app still references the image, and the cron retire loop self-heals previously stuck entries the next time it encounters them.

tests/unit/scheduler-docker-local.bats

@@ -264,3 +264,47 @@ teardown() {
   echo "status: $status"
   assert_output "$TEST_APP.web.1"
 }
+
+@test "(scheduler-docker-local) ps:rebuild with image-based deploy keeps running image" {
+  run create_app
+  echo "output: $output"
+  echo "status: $status"
+  assert_success
+
+  run /bin/bash -c "dokku checks:set $TEST_APP wait-to-retire 1"
+  echo "output: $output"
+  echo "status: $status"
+  assert_success
+
+  run /bin/bash -c "dokku git:from-image $TEST_APP cockpithq/cockpit:core-latest"
+  echo "output: $output"
+  echo "status: $status"
+  assert_success
+
+  local running_image
+  running_image="$(docker container inspect "$TEST_APP.web.1" --format '{{.Image}}' | cut -d: -f2)"
+  [[ -n "$running_image" ]]
+
+  run /bin/bash -c "dokku ps:rebuild $TEST_APP"
+  echo "output: $output"
+  echo "status: $status"
+  assert_success
+
+  sleep 3
+
+  run /bin/bash -c "dokku ps:retire"
+  echo "output: $output"
+  echo "status: $status"
+  assert_success
+  assert_output_contains "has running containers, skipping rm" 0
+
+  run /bin/bash -c "test -f /var/lib/dokku/data/scheduler-docker-local/dead-images && grep -c \"$running_image\" /var/lib/dokku/data/scheduler-docker-local/dead-images || echo 0"
+  echo "output: $output"
+  echo "status: $status"
+  assert_output "0"
+
+  run /bin/bash -c "docker container inspect $TEST_APP.web.1 --format '{{.State.Status}}'"
+  echo "output: $output"
+  echo "status: $status"
+  assert_output "running"
+}