Confidence update feeding memory store

[CodeBuildder]

Context

Updates per-action-type confidence in the memory store based on calibration outcomes. Parent: #42.

Acceptance Criteria

• After each calibration record, recorder posts a confidence update to the memory store
• Confidence update adjusts the rolling Brier score for the action type
• Action types with Brier score > 0.25 are flagged as low_confidence in the world model
• Unit test: 5 correct predictions → confidence increases; 1 wrong prediction → decreases

Dependencies

Blocked by: none | Blocks: none

Notes

No model tier.