Add extraction signal history tracking (success_rate trend over time)

[ProtocolWarden]

Auto-generated by Operations Center execution.

Goal

Add extraction signal history tracking (success_rate trend over time)

Definition of done (complete ALL before finishing)

1. Complete the task in its ENTIRETY — every acceptance criterion and every
   file the task implies (implementation, tests, and docs as applicable). Do
   not leave TODOs, stubs, or 'follow-up' gaps; a partial change is rejected
   in review.
2. Add or update tests/checks that prove the work is correct.
3. Run the repository's test suite and linters/formatters and make them
   pass locally. If anything fails, fix it before finishing — do not hand
   off a red build.
4. Only consider the task done when the full change is in place AND verified
   green. The PR you open should be mergeable as-is.

[ProtocolWarden]

Needs human attention (reason=ci_misconfigured_check). Left open — not merged (unresolved) and not closed (work preserved).

CI has not gone green after 20 checks (2 failing: audit: failure, Type check (ty): failure). Not merged (red CI) and not closed (work preserved) — needs a human to fix CI.