Keep availability recovery from stealing unrelated replacements

In fresh Stress Dynamo, Deputy 11 was toggled unavailable then available. Availability recovery unexpectedly displaced Councillor 09’s already accepted full-meeting replacement Deputy 13 and changed the seat back to a pending invitation for Deputy 11, reducing full replacements from 4 to 3. Restoring availability may re-enter ordering for unresolved invitations but must not steal or rewrite unrelated accepted assignments. Cover duplicate/multi-list deputy roles and accepted full/partial invitations.