Remove files copying

This process is very slow and buggy.

Replace in with strict check of output directory doesn't exists.
Also add `--force` flag for the bravest.

Locate the CLI command responsible for copying files and inspect how it handles the output directory. Clarify the intended strict existence check and the behavior of the proposed --force flag with a maintainer, then verify the slow or buggy copying process is replaced without changing unrelated commands.

Written by the indexing model from the issue text.