Fixing KIO copy to USB stick and network filesystems

KDE's KIO, the layer under Dolphin, now makes copies to USB sticks and network shares finish when data is actually on the device, fixing a 2011 bug (281270) where progress only reflected the page cache. Méven Car's fix uses sync_file_range() with an adaptive writeback window, plus a final flush; moves keep sources until it succeeds. It ships in Frameworks 6.32. The performance figures, such as 1.7-second listings on a 5 MB/s SMB link, are the author's own measurements on one test setup.