Deferred review findings from PR #12117: fix(ci): retry the failure watcher's job-log download once (#12112)

Verified review findings from PR #12117 by qwen-code-dev-bot whose fixes lie outside that PR's footprint, deferred by the autofix loop for follow-up. Each rc: item links back to its original review comment. A maintainer or the PR author can turn any item into its own issue/PR and apply the ready-for-agent flow to that issue — nothing here is scheduled automatically.

• rc:4042051769 .github/workflows/main-ci-failure-issue.yml: Verified real against the helper: the plan branch picks exactly one marker class (main-failure-signature.mjs:416-418), the per-commit body carries only qwen-main-ci-failure: (:222) and the per-test body only the -sig:/-test: markers (:283-285), so restoring the download re-activates a dedupe class that is disjoint in both directions from the per-commit stubs filed since gh 2.97. The fix (a workflow-scoped bridging marker as the last searchMarkers entry in both arms, inside the MAX_SEARCH_MA — comment