Fix repository URLs in README and package metadata

[SinghCod3r]

Some repository URLs still reference the old skillfoundry/skillfoundry location.

Update README.md and pyproject.toml to use:
https://github.com/SinghCod3r/SkillFoundry

Acceptance criteria:

• No incorrect repository URLs remain.
• Clone instructions work.
• Package metadata points to the correct repository.
• Tests continue to pass.