Fix autorotate axis locking, scale, and vertical yaw

[Ethanout]

Summary

• derive autorotation facing from the carrier quad basis
• apply pitch and yaw metadata bits independently so single-axis modes lock the other axis
• recover yaw from the quad horizontal axis when vertical pitch removes the facing vector's horizontal projection
• apply the carrier quad scale consistently in both autorotate and off modes
• preserve additive color-controlled rotation
• make the regression suite discoverable by the default unittest command

Tests

• python tests/test_autorotate_shader.py -v (8 tests passed)
• python -m unittest discover -v (8 tests passed)
• git diff --check

Fixes #118