Apply aerodynamic drag opposite relative airflow

[rhorvath02]

Finding

CFDAeroMap always applied drag along negative body X. That is wrong for reverse travel, a following wind faster than the vehicle, or crosswind: drag must oppose the vehicle-relative airflow vector.

Fix

Normalize the body-frame relative-air velocity and apply the positive tabulated drag magnitude opposite that direction. Downforce and calibrated moments remain on their existing body axes; documentation calls out that large flow angles still extrapolate forward-flow CFD tables.

Validation

• Reverse travel and following-wind cases both produced +13 N body-X drag.
• A 45-degree crosswind case produced 26 N drag with components {-18.3848, +18.3848} N and retained -260 N body-Z downforce.
• Drag power was negative for reverse travel, following wind, and crosswind; zero relative airflow produced exactly zero force.
• The directional aero model matched all 147/147 initialization-baseline values.
• Current-main VehicleSim matched all 1018/1018 initialization-baseline values.
• A full VehicleSim run initialized without homotopy, terminated normally on the QSS plateau at 6.098631 s, retained only finite outputs, and kept minimum tire load positive at 182.83 N.
• Ruff, Modelica lint, Python tests, and the full OpenModelica translation sweep passed locally.