Scheduled sync: main → develop

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Automated sync needs review:

• Merge conflicted: true
• Direct push exit code: n/a
  Please resolve and merge to bring develop up to date with main.

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Note

Low Risk
Documentation-only changes that clarify parameter meaning/requirements; no runtime logic or validation behavior is modified.

Overview
Clarifies the BETDisk.initial_blade_direction documentation to specify it is a global mesh-frame direction vector (not disk-local), must be orthogonal to Cylinder.axis, and is required for unsteady BET Line runs (blade_line_chord > 0).

Updates the corresponding from_c81/from_dfdc/from_xfoil/from_xrotor constructor docstrings to match this refined definition.

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