[Hotfix 25.9]: fix(): Fix coordinate transformation writes to frozen BETDisk fields

[github-actions]

Hotfix of PR #1979 (#1979) to the release-candidate/25.9 branch.
Hey @benflexcompute, please review this hotfix PR created from your original PR.

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Note

Medium Risk
Touches recursive coordinate-system transformation logic used during translation; while behavior should be equivalent, conditional mutation could affect edge cases where callers relied on always reassigning list/tuple fields.

Overview
Fixes apply_coordinate_system_transformations to avoid reassigning list/tuple fields unless at least one element actually changes, preventing writes to frozen non-entity sequences (e.g., BETDisk numeric arrays) during coordinate-system expansion.

Adds a regression test covering a BETDisk with coordinate-system-assigned entities, asserting the entity is transformed while unrelated frozen sequence fields (mach_numbers, twists, chords) remain unchanged.

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