feat(use-case-compiler): MC-based compliance questionnaires with scoring

Implements the Use-Case Compiler that turns Master Controls into
interactive compliance audits. 5 templates (Vendor Check, SAST/DAST,
DSGVO, NIS2, CRA), deterministic + LLM question generation, scoring
engine with regulation/severity breakdown, and gap detection.

- Backend: 9 API endpoints, 22 unit tests (all pass)
- Frontend: Template selector, questionnaire, result dashboard
- Migration 027: usecase_audits + usecase_answers tables

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

ai-compliance-sdk/internal/usecase/scoring.go

@@ -0,0 +1,92 @@
+package usecase
+
+// Score calculates a compliance score from answers and questions.
+func Score(audit *Audit, answers []Answer) *ScoreResult {
+	result := &ScoreResult{
+		AuditID:        audit.ID,
+		TotalQuestions: len(audit.Questions),
+		ByRegulation:   make(map[string]RegulationScore),
+		BySeverity:     make(map[string]SeverityScore),
+	}
+
+	answerMap := make(map[string]Answer)
+	for _, a := range answers {
+		answerMap[a.QuestionID] = a
+	}
+
+	for _, q := range audit.Questions {
+		a, answered := answerMap[q.ID]
+		if !answered {
+			continue
+		}
+
+		result.Answered++
+
+		passed := isPassed(a)
+		switch a.Status {
+		case AnswerStatusSkipped:
+			result.Skipped++
+		default:
+			if passed {
+				result.Passed++
+			} else {
+				result.Failed++
+			}
+		}
+
+		// By regulation
+		if q.Regulation != "" {
+			rs := result.ByRegulation[q.Regulation]
+			rs.Total++
+			if passed {
+				rs.Passed++
+			}
+			result.ByRegulation[q.Regulation] = rs
+		}
+
+		// By severity
+		sev := q.Severity
+		if sev == "" {
+			sev = "MEDIUM"
+		}
+		ss := result.BySeverity[sev]
+		ss.Total++
+		if passed {
+			ss.Passed++
+		} else {
+			ss.Failed++
+		}
+		result.BySeverity[sev] = ss
+	}
+
+	// Calculate scores
+	if result.Answered > 0 {
+		answerable := result.Answered - result.Skipped
+		if answerable > 0 {
+			result.ComplianceScore = float64(result.Passed) / float64(answerable) * 100
+		}
+	}
+
+	for reg, rs := range result.ByRegulation {
+		if rs.Total > 0 {
+			rs.Score = float64(rs.Passed) / float64(rs.Total) * 100
+		}
+		result.ByRegulation[reg] = rs
+	}
+
+	return result
+}
+
+// isPassed checks if an answer represents a pass.
+func isPassed(a Answer) bool {
+	switch v := a.Value.(type) {
+	case bool:
+		return v
+	case string:
+		return v == "yes" || v == "true" || v == "ja"
+	case float64:
+		return v > 0
+	default:
+		return false
+	}
+}