Ford doesn't work when installed using nix/nixos

There's following problem. All data installed by nix is marked read-only both files and directories. And when ford copies static data using shutils permissions are preserved. So when kord tries to write data into read-only directories it predictably fails.

I have small patch which add write by owner bit after copying and it fixes this issue.

Reproduce Ford installed through nix/NixOS and trace the static-data copy path used by shutil. Confirm that copied files and directories can be written by Ford at runtime, then run the repository's available tests or a minimal documentation-generation check to verify the installation no longer fails.

Written by the indexing model from the issue text.