Cleanup: Remove unused imports in Snakefile

[cmkobel]

Summary

In workflow/Snakefile (lines ~21–24):

• copyfile from shutil is imported but never called anywhere in the Snakefile
• csv is commented out with # Can be disabled?

There's also a TODO comment: # TODO: Test disabling these: above the import block, suggesting this was already recognized but never acted on.

Proposed approach

Remove the unused copyfile import and the commented-out csv import line. Verify no rules rely on these imports being available in scope.

Files to touch

• workflow/Snakefile (lines ~21–24)