updates & more test

[ianscrivener]

• STL codec bug fixes — patched issues in the STL export codec affecting reliability
• Minimum Python bumped to 3.11 — updated pyproject.toml and CI workflows; also updated black and click dependencies
• uv.lock added — full lockfile committed to pin all dependency versions
• 28 new tests added — test suite now at 623 total, with expanded coverage across STL, STEP, GLTF, GLB, SVG codecs
• New test fixtures added — cube_params_no_default.py, multi_show_object.py, and syntax_error.py for edge-case coverage
• CLI test expansion — test_cli.py grew significantly covering more command combinations and error paths
• New TECH_README.md created — 61-line technical reference document added alongside the existing README
• README overhauled — major rewrite to reflect current state of the project

[jmwright]

I should probably publish cq-cli on PyPI. I'm not sure why I have not. Maybe I'll create a new release and do that after these changes are merged.

[jmwright]

Thanks for all the work you have put into this @ianscrivener !

I made a few comments and approved the CI to run, which surfaced a few things (lint and tests).

[ianscrivener]

Done

[jmwright]

@ianscrivener There are a few CI issues to fix, but I think we're close to merging.

[ianscrivener]

CI/CD complete...

[jmwright]

@ianscrivener It seems like the CI/CD section that is in the readme right now would go better on the tech_readme.

[jmwright]

Thanks for this @ianscrivener . We can decide to move the CI/CD section later, if needed.