Use CPU engines with graphics for all KCL execution

[bcorey]

All instances of ExecutorSettings in CLI are sourced from two helper methods, one for kcl commands and one for "copilot" commands. Made sure that the KCL helper always sets geo_only=true. the copilot/ZK helper has been left alone. Set the pool to "cpu" when geometry_only is true.

Because the CLI can execute arbitrary KCL and some KCL cannot run on an engine with no graphics context, I've enabled graphics for all KCL execution modes.

Tests have the same outcomes as on main. That means all but 1 succeed when pointed at the dev environment, and all but 36 succeed when pointed at prod. Added clarification to the README on how to set the token and host for the test run.

Mike's work to emulate graphics on the CPU engines made this a lot easier than it was going to be. But because the GLB-based CPU renderer is so handy for troubleshooting export issues, I will still be adding that as an alternative render option for KCL commands in an upcoming PR so file format team and others working on rendering can quickly get visual export quality feedback.

[codecov]

Codecov Report

❌ Patch coverage is 63.15789% with 7 lines in your changes missing coverage. Please review.
✅ Project coverage is 67.92%. Comparing base (2307f86) to head (db0eb7f).
⚠️ Report is 2 commits behind head on main.

Files with missing lines	Patch %	Lines
src/context.rs	58.82%	7 Missing ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##             main    #1898      +/-   ##
==========================================
+ Coverage   67.90%   67.92%   +0.02%     
==========================================
  Files          43       43              
  Lines        8705     8718      +13     
==========================================
+ Hits         5911     5922      +11     
- Misses       2794     2796       +2     

Flag	Coverage Δ
unittests	67.92% <63.15%> (+0.02%)	⬆️

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