Parse KCL measurement units consistently

[JordanNoone]

KCL measurement arguments parse directly into the modeling-command unit enums for volume, mass, density, surface area, center of mass, bounding boxes, and combined analysis. Enable the crate's clap feature and require kittycad-modeling-cmds >= 0.2.230, which includes volume's ValueEnum support and preserves existing unit abbreviations, defaults, and density aliases. The lockfile retains the published 0.2.231 already used by current main; the temporary Git patch and volume conversion helper are gone.

Regression coverage exercises all 14 measurement-unit flags: 71 accepted flag/value combinations and 14 invalid-value diagnostics with the exact available choices. It also checks file/KCL volume parity, analysis defaults, and all six density spellings across four flags.

Validation:

• cargo test cmd_kcl::tests:: --locked --offline: 7 passed, 0 failed.
• cargo clippy --all-features --all-targets --locked --offline -- -D warnings: passed.
• cargo fmt --all -- --check and git diff --check: passed.
• Updated the Nix vendor hash from checksummed crate tarballs and the exact Git dependency tree; verified the calculation by reproducing current main's existing hash. Full Nix builds run in CI.

The local tests exercise command parsing and settings without live Engine/API requests.

Fixes #1744

[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 66.62%. Comparing base (6733975) to head (3db37ab).

Additional details and impacted files

@@            Coverage Diff             @@
##             main    #1844      +/-   ##
==========================================
+ Coverage   66.18%   66.62%   +0.44%     
==========================================
  Files          43       43              
  Lines        8451     8563     +112     
==========================================
+ Hits         5593     5705     +112     
  Misses       2858     2858              

Flag	Coverage Δ
unittests	66.62% <100.00%> (+0.44%)	⬆️

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[adamchalmers]

Pls do not merge, hold for proper review

[adamchalmers]

Please retarget this branch to deserialize command-line args for UoM via the kittycad-modeling-cmds crate (released in version 0.2.229) rather than implementing conversions between them.

[adamchalmers]

kcmc v0.2.229 was released with the clap derive now so you can remove the crates.io patch.

Why does only volume need special treatment here, should this apply to all units? Genuine question.