YawSync XML range does not match either angular convention used elsewhere

Describe the bug
create_xml_file uses two self-consistent angular conventions: signed symmetric for Roll and Pitch (-180/180) and unsigned compass for Heading (0/360). YawSync is -180/360 (relay/src/update.rs:262-263), which matches neither and spans 540 degrees.

Expected behavior
Yaw uses the unsigned compass convention, 0/360. Yaw comes from sim/flightmodel/position/psi (xplane_plugin/src/pilotdatasync-xp11.cpp:212), which is X-Plane's true heading, not a signed angle like phi and theta. In the committed flight data (inference/Data/labeled_flight_data.csv, 16,604 rows) yaw ranges from 0.55 to 359.96 and is never negative. An earlier version of this issue suggested -180/180, which would put half of the real values out of range.

Additional context
Full inventory: Altitude 0/50000, Airspeed 0/600, VerticalVelocity -5000/5000, Heading 0/360, Roll -180/180, Pitch -180/180, Yaw -180/360, GForce -10/10. Worth confirming against iMotions before changing, since the range affects graph scaling.

Found while writing the setup documentation in #138 / #178.