feat(msp): add MSP2_INAV_WIND (0x2231) to expose wind estimator

[MartinovEm]

Summary

Adds a new read-only MSP command MSP2_INAV_WIND (ID 0x2231) that exposes the internal wind estimator output over MSP telemetry.

This allows ground station software, OSD overlays, and companion computers to read the estimated wind speed and direction without requiring direct firmware integration.

Response Payload

Byte offset	Type	Name	Unit	Notes
0–1	uint16	windSpeed	cm/s	Estimated horizontal wind speed
2–3	uint16	windAngle	degrees	Wind direction (0–359°, 0 = North)

Total: 4 bytes.

Implementation Details

• getEstimatedHorizontalWindSpeed() returns angle in centidegrees [0–35999]; divided by 100 to give 0–359° output.
• Guarded by USE_WIND_ESTIMATOR: when the estimator is not compiled in, both fields return zero, ensuring backward-compatible behaviour on builds without wind estimation.
• The #include "flight/wind_estimator.h" in fc_msp.c is also wrapped in #ifdef USE_WIND_ESTIMATOR.

Files Changed

• src/main/msp/msp_protocol_v2_inav.h — defines MSP2_INAV_WIND 0x2231
• src/main/fc/fc_msp.c — conditional include + new case MSP2_INAV_WIND: handler