ci: stop disk reclaim from deleting a smoke image mid-test

v1.12.2 run 740: build-variant's `docker system prune -af --volumes`
untagged pi-devbox:smoke-studio 30 ms after smoke-studio loaded it, so
every studio assertion failed and the -studio tags were not published.
All jobs share the runner's Docker daemon, and a smoke image is unused
between smoke-test.sh's one-shot `docker run`s.

- scripts/ci-reclaim-docker.sh: the same reclaim, per object type, but
  never prunes an image labelled se.jordbo.pi-devbox.ci-smoke-image;
  labelled orphans are swept after 6h. `assert-protected IMG` is the
  smoke preflight; `lint WORKFLOW...` rejects raw system/image prunes.
- smoke jobs: label their image, assert it, tag it per run
  (pi-devbox:smoke[-studio]-<run_id>), remove it in an always() step.
- all five reclaim sites call the script; lint.yml runs the guard.
- Job order unchanged: studio jobs still gate only the -studio tags.

Verified on an isolated docker:29-dind (old prune deletes a labelled
image; new reclaim keeps it, removes unlabelled + 1970-created labelled
images, spares an in-use image, no errors); actionlint, shellcheck,
lint-shell, check-workflow-shell, check-doc-drift all clean.

.gitea/workflows/lint.yml

@@ -90,6 +90,14 @@ jobs:
         # actionlint so the more precise diagnostic surfaces first.
         run: bash scripts/check-workflow-shell.sh .gitea/workflows
 
+      - name: No raw docker prune in workflows (shared runner daemon)
+        # Every docker-publish.yml job shares the runner's Docker daemon, and
+        # a bare `docker system prune -a` in one job deletes the smoke image
+        # another job is testing (v1.12.2 run 740 shipped without its -studio
+        # tags that way). Reclaim goes through scripts/ci-reclaim-docker.sh,
+        # which spares labelled smoke images; this keeps it that way.
+        run: bash scripts/ci-reclaim-docker.sh lint .gitea/workflows/*.yml
+
       - name: link-pi-models.sh contract (two-sided, no docker needed)
         # The entrypoint links ~/.pi/agent/models.json to a mounted shared file
         # and must never replace a real file or a user's own link. Tested here