Description

Allow docker cp to accept multiple source paths when the destination is a directory.
This fixes commands where shell brace expansion produces multiple source arguments, for example:

docker cp container:/home/ubuntu/{backup.tar.gz,settings.json} ~/Downloads/backups

Previously this failed because docker cp required exactly two arguments.

Changes

• Accept two or more positional arguments for docker cp
• Treat the last argument as the destination
• Validate that multi-source copies use a directory destination
• Copy each source sequentially using existing copy logic
• Add unit coverage for multi-source command and runCopy paths