Start and stop real sidecar capture from Rowing Tracker

[rupertgermann]

Parent

• PRD: Real freemocap sidecar service #68

What to build

Complete the end-to-end real capture path between Rowing Tracker and the sidecar. With the real sidecar running and ready, a user should be able to enable Multi-camera sidecar, start capture, stream real sidecar-3d pose frames into storage, stop capture, finalize the session, and open the replay/analysis using the existing mocap session lifecycle.

Acceptance criteria

• Starting sidecar capture from Rowing Tracker arms the real sidecar session and stores sidecar session metadata including camera count and calibration id where available.
• Real sidecar frames are uploaded into the existing PoseFrameStream storage path as schema-v2 world-mm-3d frames.
• Stopping capture stops the sidecar, drains any pending frames, finalizes the pose stream, and runs normal post-session analysis.
• The resulting mocap session is stored with source sidecar and capture perspective sidecar-3d.
• The session detail/replay path opens for the captured session and shows derived posture output where analysis succeeds.
• Failure during start, stream, stop, or finalize leaves a clear user-visible error and does not silently mark a bad session ready.
• Automated coverage verifies the Rowing Tracker client against a real sidecar process using the deterministic source, plus a documented hardware-gated manual smoke path for real cameras.

Blocked by

• FreeMoCap runtime adapter reads real 3D output into ADR-0005 frames #70
• Real camera health and calibration readiness gate #71