Add heading-based root rotation controls

[QihanZhao]

Summary

Add a heading-based root rotation editing mode to Base Control while preserving direct quaternion editing.

Changes

• Add root rotation decomposition helpers for Yaw Z, Pitch Side, and Roll Heading using the root local +X heading projected into the world XY plane.
• Update Base Control to show both heading decomposition controls and direct quaternion controls.
• Keep trajectory storage, keyframe residuals, interpolation, and export behavior based on quaternion values.
• Add tests for heading direction, side-axis pitch behavior, compose/decompose round trips, and direct quaternion normalization.

Test Plan

• node tests/root-rotation-decomposition-test.js
• node tests/quaternion-optimized-test.js
• node tests/verify-quaternion-order.js
• npm run build

Note: npm run build still reports the existing Vite large chunk warning.