make_2611_stages: comparator stages guard on the ArcadeDB wheel and image they do not use, and a pre-START abort strands the chain #439

The comparator stages that make_2611_stages.py writes (default mode, no ArcadeDB arm) guard on the ArcadeDB pair although they never use it, and a guard that fails before the START line leaves the whole chain waiting forever.

Found in the readiness check of 2026-10-22 (drafts qS01-qS09 core, qU01-qU03 second list). Every stage checks that bindings/python/dist/ holds exactly one wheel, the pinned 26.10.2 file, and that dbbench:arcadedb carries that wheel and the JPype pin, and runs verify_pair_c25.sh. A comparator stage builds client, duckdb, pg-age and so on, never arcadedb, and none of its arms imports arcadedb_embedded. On mini today dist/ holds only the 26.10.1 wheel and dbbench:arcadedb is the 2026-10-06 build, so qS01 would abort with "dbbench:arcadedb carries wheel 26.10.1, dist has 26.10.2".

The second problem is what that abort does. The template says "AN ABORT MUST NOT STRAND THE CHAIN" and sets the ALL-DONE trap, but it sets it after the guards, at the START line. A guard before it exits 1 without a marker, so the other eleven stages wait for qS01 ALL-DONE for good. The documented convention (the qMA stages in mini-ab-prep/DESIGN.md: "an EXIT trap set after the wait writes its own marker, so ABORT/SKIP still hand on") is that every ABORT hands on, and the ABORT line goes to STATUS.txt, which mini_watch.sh greps.

Fix, one PR:

• The pair's guards (pinned wheel by name and sha256, exactly one wheel in dist/, server image, wheel and JPype read back out of dbbench:arcadedb, verify_pair_c25.sh) go into the stages that run an ArcadeDB arm only. A comparator stage keeps exporting ARCADEDB_WHEEL, ARCADEDB_SERVER_IMAGE and ARCADEDB_ENGINE_COMMIT because the runner takes the three together and land_stage.py keeps the rows whose engine_commit matches the pin, but it exports them after its image build, so build_images.sh no longer bakes the engine under test into the comparator images.
• The ALL-DONE trap moves to right after the wait, before the first guard.
• --check --drafts lints both rules, tests cover them, the stored draft sha list is rewritten, CAMPAIGN.md says it.