Extend BANK_PRUNE_FOLDER from report-only to dry-run→confirm-with-manifest→
delete exactly the pure-core orphan set (fresh recompute, stale entries skipped).
Windows routes to Recycle Bin (SHFileOperation+FOF_ALLOWUNDO), else unlink.
New pure prune_button module + footer button dispatching the action id. No
ext-state write, no undo point (deletion is not REAPER-undoable).
