Remove stale untracked lib/python/base_cli/ __pycache__ cruft

[codeforester]

Goal

Remove the stale, untracked lib/python/base_cli/ directory (currently only
__pycache__ files with no source) left over from before base-cli was
extracted into its own PyPI package.

Background

lib/python/base_cli/ in the working tree contains only compiled
__pycache__/*.pyc files across several CPython versions and an empty
tests/ directory — there is no .py source anywhere under it, and
git ls-files lib/python/base_cli/ returns nothing, confirming it was never
tracked. Base now correctly resolves base_cli via the published
base-cli==0.4.2 dependency in requirements-dev.txt. This leftover
directory is harmless today, but a stray untracked package directory sitting
under a path that can end up on PYTHONPATH is exactly the kind of thing
that causes a confusing import-shadowing bug later, and it adds noise for
anyone inspecting lib/python/.

Scope

• Delete lib/python/base_cli/ (and its __pycache__/tests contents) from
  the working tree.
• Confirm no build, test, or PYTHONPATH-construction logic references this
  path expecting it to exist locally (it should not, since it was never
  tracked and the real dependency comes from the installed base-cli
  package).

Acceptance Criteria

• lib/python/base_cli/ no longer exists on disk after a clean checkout
  and a normal basectl setup / test run.
• basectl test base and the standalone Python test command in
  CONTRIBUTING.md still pass unchanged, confirming nothing depended on
  the stale local path.

Validation

• basectl test base
• BASE_CLI_SOURCE_DIR=../base-cli/lib/python PYTHONPATH=../base-cli/lib/python:lib/python:cli/python python -m pytest
• git status to confirm the directory was untracked before removal (no
  tracked files are being deleted)

Non-Goals

• Does not change how Base depends on base-cli (still base-cli==0.4.2 via
  requirements-dev.txt).
• Does not touch the standalone base-cli source checkout used for
  from-source Python testing per CONTRIBUTING.md.

Project Fields

Status: Backlog · Priority: P3 · Size: T · Area: Python · Initiative: Contract Hardening

Agent Assignment

Copilot candidate after triage