feat(classify): introduce incident taxonomy and risk tier scoring #2
Description
Goal
Define and implement incident classification contract for runtime failures.
Scope
- Base taxonomy: payload_invalid, auth_error, rate_limit, runtime_noise, state_drift
- Risk tier output: none/low/moderate/high
- Confidence score in [0,1]
Acceptance Criteria
- Deterministic mapping tests
- JSON output contract documented
- Unknown errors fall back to safe default classification