docs: add pre-pypi install and publish timing guidance

[aa-parky]

Summary

• add clear pre-PyPI installation guidance to README
• include exact GitHub tag install command:
  • pip install "pipeworks-ipc @ git+https://github.com/pipe-works/pipeworks_ipc.git@v0.1.1"
• document local editable path, Git tag, and commit-SHA install options
• add pyproject.toml dependency examples for consumers before PyPI
• add explicit "when to publish to PyPI" decision criteria and rollout steps
• mirror this guidance in Sphinx docs (usage.rst and project_integration.rst)

Validation

• make -C docs clean html
• pre-commit run --files README.md docs/source/usage.rst docs/source/project_integration.rst

[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.

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