Adds `deletedAt` sweep guards to the engine's self-healing and merger to prevent recovery operations from processing soft-deleted tasks, filters deleted tasks in the `recover-stale-blocked-by` script, includes a new regression test for the deadlock-scan exclusion pattern, and updates the soft-delete
Fusion-Task-Id: FN-5528
Fusion-Task-Lineage: 5c9e45ca-49a8-47a0-a23d-6fe8e15e7e00
Co-authored-by: Fusion (runfusion.ai) <noreply@runfusion.ai>
Fusion-Task-Id: FN-5528