The repository_dispatch handoff step was continue-on-error with a single
attempt: if the call failed (token lacking contents:write, transient API
error), the chain stalled silently while every job stayed green.
Each handoff now retries 3x and, if all attempts fail, files an alert
issue in rustfs/backlog with the exact recovery command before exiting 1
(still continue-on-error, so suite workflows themselves never fail).