Replaces the shared IsBusy/IsMerging flags in WorktreesOverviewModalViewModel and the
reset flow in WorktreesSettingsTabViewModel with dedicated OperationStatus instances
shown via OperationIndicator, so a running Refresh no longer blocks the Cleanup
indicator. ForceRemove gains a CanExecute guard against re-entrancy while it's running,
and the reconcile tick's busy guard now checks all four action statuses instead of the
old IsBusy||IsMerging pair.
The RequestConflictResolution Func was declared on 5 VMs and hand-threaded shell->details->merge-section->diff->merge-modal. Replaced with a DI-singleton IMergeCoordinator (MergeCoordinator holder; shell wires its Handler at composition, breaking the shell<->island cycle). Invokers (MergeModal, DetailsIsland, WorktreesOverview) depend on the interface; the two pass-through VMs (DiffModal, MergeSection) drop the seam entirely. No behavior change; conflict-seam + batch tests rewired to assert via the coordinator.
Mika Kuns