Adds auto-recovery for merge deadlocks when candidates have already been merged on main (FN-3857), including tests, documentation updates in AGENTS.md, and a patch changeset for the `@runfusion/fusion` package. Fusion-Task-Id: FN-3857
Adds auto-recovery for merge deadlocks when candidates have already been merged on main (FN-3857), including tests, documentation updates in AGENTS.md, and a patch changeset for the `@runfusion/fusion` package. Fusion-Task-Id: FN-3857