FLO-27: non-panicking fixReschedule with stale UUID self-cleanup

[holyfuchs]

Closes: #236

• FlowALPRebalancerPaidv1.fixReschedule(uuid:) returned Void and force-unwrapped borrowRebalancer(uuid)!. A stale UUID (rebalancer deleted without removing from the Supervisor set) caused a panic, reverting the entire executeTransaction and blocking recovery for all other paid rebalancers in that run.
• fixReschedule now returns Bool — true if the rebalancer was found and processed, false if the UUID no longer exists.
• The Supervisor's executeTransaction loop checks the return value; on false it calls removePaidRebalancer to self-clean the stale entry, so subsequent ticks are not affected.

[liobrasil]

closes #236