[Maintenance] Record packaging updates and install from the lockfile in CI

[terrancedejesus]

Summary

• Record [Maintenance] Ignore local AI and planning markdown #90, [Maintenance] Pin Python dependencies to current 3.10-compatible versions #91, and [Maintenance] Refresh ReadTheDocs requirements for pinned Sphinx #92 in the unreleased changelog.
• Pin Poetry 2.3.3 in GitHub Actions and run poetry check --lock before poetry install.
• Remove the invalid Topic :: Google Workspace classifier so the lockfile check can succeed.

Test plan

• poetry check --lock exits 0
• CI pytest job installs from poetry.lock on Python 3.10
• Changelog entries for [Maintenance] Ignore local AI and planning markdown #90, [Maintenance] Pin Python dependencies to current 3.10-compatible versions #91, and [Maintenance] Refresh ReadTheDocs requirements for pinned Sphinx #92 render on ReadTheDocs