WinRacing V51.2 — Supreme Confidence Calibration

Added
- Reliability-weighted confidence calibration over immutable V50 output.
- Dynamic disagreement index across V50 confidence, consensus and stability.
- Disagreement penalty and calibration reliability score.
- Daily mean shrinkage to reduce overconfidence from weak/contradictory signals.
- Confidence uncertainty band (low/high) and calibration status.
- Dashboard calibration health and per-race calibration trace.

Unchanged
- V44-V50 score formulas and betting logic.
- Database schema. No CREATE/ALTER/DROP.
- Existing V51 source-date and V50 run-key trace.
