feat: AI Act Decision Tree — Zwei-Achsen-Klassifikation (GPAI + High-Risk)

Interaktiver 12-Fragen-Entscheidungsbaum für die AI Act Klassifikation
auf zwei Achsen: High-Risk (Anhang III, Q1-Q7) und GPAI (Art. 51-56, Q8-Q12).
Deterministische Auswertung ohne LLM.

Backend (Go):
- Neue Structs: GPAIClassification, DecisionTreeAnswer, DecisionTreeResult
- Decision Tree Engine mit BuildDecisionTreeDefinition() und EvaluateDecisionTree()
- Store-Methoden für CRUD der Ergebnisse
- API-Endpoints: GET/POST /decision-tree, GET/DELETE /decision-tree/results
- 12 Unit Tests (alle bestanden)

Frontend (Next.js):
- DecisionTreeWizard: Wizard-UI mit Ja/Nein-Fragen, Dual-Progress-Bar, Ergebnis-Ansicht
- AI Act Page refactored: Tabs (Übersicht | Entscheidungsbaum | Ergebnisse)
- Proxy-Route für decision-tree Endpoints

Migration 083: ai_act_decision_tree_results Tabelle

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

ai-compliance-sdk/internal/ucca/store.go

@@ -358,6 +358,128 @@ type AssessmentFilters struct {
 	Offset      int // OFFSET for pagination
 }
 
+// ============================================================================
+// Decision Tree Result CRUD
+// ============================================================================
+
+// CreateDecisionTreeResult stores a new decision tree result
+func (s *Store) CreateDecisionTreeResult(ctx context.Context, r *DecisionTreeResult) error {
+	r.ID = uuid.New()
+	r.CreatedAt = time.Now().UTC()
+	r.UpdatedAt = r.CreatedAt
+
+	answers, _ := json.Marshal(r.Answers)
+	gpaiResult, _ := json.Marshal(r.GPAIResult)
+	obligations, _ := json.Marshal(r.CombinedObligations)
+	articles, _ := json.Marshal(r.ApplicableArticles)
+
+	_, err := s.pool.Exec(ctx, `
+		INSERT INTO ai_act_decision_tree_results (
+			id, tenant_id, project_id, system_name, system_description,
+			answers, high_risk_level, gpai_result,
+			combined_obligations, applicable_articles,
+			created_at, updated_at
+		) VALUES (
+			$1, $2, $3, $4, $5,
+			$6, $7, $8,
+			$9, $10,
+			$11, $12
+		)
+	`,
+		r.ID, r.TenantID, r.ProjectID, r.SystemName, r.SystemDescription,
+		answers, string(r.HighRiskResult), gpaiResult,
+		obligations, articles,
+		r.CreatedAt, r.UpdatedAt,
+	)
+	return err
+}
+
+// GetDecisionTreeResult retrieves a decision tree result by ID
+func (s *Store) GetDecisionTreeResult(ctx context.Context, id uuid.UUID) (*DecisionTreeResult, error) {
+	var r DecisionTreeResult
+	var answersBytes, gpaiBytes, oblBytes, artBytes []byte
+	var highRiskLevel string
+
+	err := s.pool.QueryRow(ctx, `
+		SELECT id, tenant_id, project_id, system_name, system_description,
+			answers, high_risk_level, gpai_result,
+			combined_obligations, applicable_articles,
+			created_at, updated_at
+		FROM ai_act_decision_tree_results WHERE id = $1
+	`, id).Scan(
+		&r.ID, &r.TenantID, &r.ProjectID, &r.SystemName, &r.SystemDescription,
+		&answersBytes, &highRiskLevel, &gpaiBytes,
+		&oblBytes, &artBytes,
+		&r.CreatedAt, &r.UpdatedAt,
+	)
+
+	if err == pgx.ErrNoRows {
+		return nil, nil
+	}
+	if err != nil {
+		return nil, err
+	}
+
+	json.Unmarshal(answersBytes, &r.Answers)
+	json.Unmarshal(gpaiBytes, &r.GPAIResult)
+	json.Unmarshal(oblBytes, &r.CombinedObligations)
+	json.Unmarshal(artBytes, &r.ApplicableArticles)
+	r.HighRiskResult = AIActRiskLevel(highRiskLevel)
+
+	return &r, nil
+}
+
+// ListDecisionTreeResults lists all decision tree results for a tenant
+func (s *Store) ListDecisionTreeResults(ctx context.Context, tenantID uuid.UUID) ([]DecisionTreeResult, error) {
+	rows, err := s.pool.Query(ctx, `
+		SELECT id, tenant_id, project_id, system_name, system_description,
+			answers, high_risk_level, gpai_result,
+			combined_obligations, applicable_articles,
+			created_at, updated_at
+		FROM ai_act_decision_tree_results
+		WHERE tenant_id = $1
+		ORDER BY created_at DESC
+		LIMIT 100
+	`, tenantID)
+	if err != nil {
+		return nil, err
+	}
+	defer rows.Close()
+
+	var results []DecisionTreeResult
+	for rows.Next() {
+		var r DecisionTreeResult
+		var answersBytes, gpaiBytes, oblBytes, artBytes []byte
+		var highRiskLevel string
+
+		err := rows.Scan(
+			&r.ID, &r.TenantID, &r.ProjectID, &r.SystemName, &r.SystemDescription,
+			&answersBytes, &highRiskLevel, &gpaiBytes,
+			&oblBytes, &artBytes,
+			&r.CreatedAt, &r.UpdatedAt,
+		)
+		if err != nil {
+			return nil, err
+		}
+
+		json.Unmarshal(answersBytes, &r.Answers)
+		json.Unmarshal(gpaiBytes, &r.GPAIResult)
+		json.Unmarshal(oblBytes, &r.CombinedObligations)
+		json.Unmarshal(artBytes, &r.ApplicableArticles)
+		r.HighRiskResult = AIActRiskLevel(highRiskLevel)
+
+		results = append(results, r)
+	}
+
+	return results, nil
+}
+
+// DeleteDecisionTreeResult deletes a decision tree result by ID
+func (s *Store) DeleteDecisionTreeResult(ctx context.Context, id uuid.UUID) error {
+	_, err := s.pool.Exec(ctx, "DELETE FROM ai_act_decision_tree_results WHERE id = $1", id)
+	return err
+}
+
 // ============================================================================
 // Helpers
 // ============================================================================