Remove the duplicate nested base-cli README

[codeforester]

Problem

lib/python/base_cli/README.md is a tracked near-duplicate of the top-level README, is not referenced by the package metadata or validation scripts, and has already begun to drift from the canonical documentation.

Scope

• Delete the unreferenced nested README.
• Verify the top-level README remains the only packaged/documented README and all documentation checks still pass.

Acceptance criteria

• No repository tooling or package metadata references the nested README.
• The canonical top-level README remains complete and current.