CONTRIBUTING.md uses basectl commands inaccessible to external contributors

[codeforester]

Problem

CONTRIBUTING.md:46–48 instructs contributors to run:

basectl check base-cli
basectl doctor base-cli
basectl test base-cli

basectl is a product tool from the Base workspace platform that external contributors do not have. An outside contributor who clones the repository, reads CONTRIBUTING.md, and follows step 6 ("Run the project checks before opening or updating a pull request") cannot run these commands.

This makes the project effectively closed to external contribution despite its open-source Apache-2.0 license.

Fix

Add a "Development setup" section to CONTRIBUTING.md immediately before the workflow steps with the standard Python commands:

# Install the package with development and quality dependencies
python -m pip install -e ".[dev,quality]"

# Run the test suite
python -m pytest

# Run the linter
ruff check lib/python/base_cli scripts examples tests

# Run the type checker
mypy --strict lib/python/base_cli

# Build the package
python -m build

The basectl commands can remain as the preferred shortcut for Base workspace users, but each should be followed by the equivalent portable command, or linked to a section that explains the equivalents.