Add HCDF v2.0 schema with ports, sensors, and geometry

- Add optical-flow HCDF with full v2 schema including:
  - Ports (ETH0, CAN0) with box geometry
  - Sensors with type-specific geometry (cone for optical flow, frustum for ToF)
  - IMU sensors with axis-align for driver configuration
  - Magnetometer and barometer sensors
- Add comprehensive schema-reference.md documentation
- Update symlink to point to new SHA-prefixed version

Signed-off-by: Benjamin Perseghetti <bperseghetti@rudislabs.com>

Author: bperseghetti