Adds GET /projects/:id/risk-matrix — a confidence-aware risk view computed
on read from each hazard's category/scenario/lifecycle using the SAME model
as the GT benchmark (no persistence, so it never goes stale against the
model; the hand-defaulted iace_hazards risk columns stay untouched).
- risk_matrix.go: EstimateHazardRisk (single source of truth for S/F/W/P +
range + level + confidence) and BuildRiskMatrix (per-hazard list + a 5×5
Severity×Probability aggregation grid with dominant level per cell).
- Frontend: RiskMatrix grid in the Risikobewertung tab (muted colours per
the confidence-aware tonality), level counts + tool-confidence summary,
fed by useRiskMatrix. Shows risk for EVERY project, not only GT ones.
Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>