* fix(sftp): use remote cp for fresh same-host copies (Fixes#4207)
Ordinary SFTP tasks were marked resumable, which skipped the existing file and directory cp optimizations. Select the non-resumable route only when creating fresh matching-host copies with eligible encodings, keeping transfer-center rows and recursive children consistent. Existing checkpointed transfers retain their saved resumable path; failed cp attempts retain the download/upload fallback.
* fix(sftp): skip same-host directory cp when auto encoding resolves to non-UTF-8
* fix(sftp): preserve dest mode when same-host cp replaces a file
* fix(sftp): skip same-host cp for symlinks and directory merges
* test(sftp): mock missing dest in same-host cp cache fixture
* fix(sftp): expose lstat on session-backed copy clients
陈大猫
3096f86889