refactor(go/ucca): split license_policy, models, pdf_export, escalation_store, obligations_registry

Split 5 oversized files (501-583 LOC each) into focused units all under 500 LOC:
- license_policy.go → +_types.go (engine logic / type definitions)
- models.go → +_intake.go, +_assessment.go (enums+domains / intake structs / output+DB types)
- pdf_export.go → +_markdown.go (PDF export / markdown export)
- escalation_store.go → +_dsb.go (main escalation ops / DSB pool ops)
- obligations_registry.go → +_grouping.go (registry core / grouping methods)

All files remain in package ucca. Zero behavior changes.

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

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

@@ -0,0 +1,75 @@
+package ucca
+
+import "time"
+
+// ============================================================================
+// Grouping Methods
+// ============================================================================
+
+// GroupByRegulation groups obligations by their regulation ID
+func (r *ObligationsRegistry) GroupByRegulation(obligations []Obligation) map[string][]Obligation {
+	result := make(map[string][]Obligation)
+	for _, obl := range obligations {
+		result[obl.RegulationID] = append(result[obl.RegulationID], obl)
+	}
+	return result
+}
+
+// GroupByDeadline groups obligations by deadline timeframe
+func (r *ObligationsRegistry) GroupByDeadline(obligations []Obligation) ObligationsByDeadlineResponse {
+	result := ObligationsByDeadlineResponse{
+		Overdue:     []Obligation{},
+		ThisWeek:    []Obligation{},
+		ThisMonth:   []Obligation{},
+		NextQuarter: []Obligation{},
+		Later:       []Obligation{},
+		NoDeadline:  []Obligation{},
+	}
+
+	now := time.Now()
+	oneWeek := now.AddDate(0, 0, 7)
+	oneMonth := now.AddDate(0, 1, 0)
+	threeMonths := now.AddDate(0, 3, 0)
+
+	for _, obl := range obligations {
+		if obl.Deadline == nil || obl.Deadline.Type != DeadlineAbsolute || obl.Deadline.Date == nil {
+			result.NoDeadline = append(result.NoDeadline, obl)
+			continue
+		}
+
+		deadline := *obl.Deadline.Date
+		switch {
+		case deadline.Before(now):
+			result.Overdue = append(result.Overdue, obl)
+		case deadline.Before(oneWeek):
+			result.ThisWeek = append(result.ThisWeek, obl)
+		case deadline.Before(oneMonth):
+			result.ThisMonth = append(result.ThisMonth, obl)
+		case deadline.Before(threeMonths):
+			result.NextQuarter = append(result.NextQuarter, obl)
+		default:
+			result.Later = append(result.Later, obl)
+		}
+	}
+
+	return result
+}
+
+// GroupByResponsible groups obligations by responsible role
+func (r *ObligationsRegistry) GroupByResponsible(obligations []Obligation) map[ResponsibleRole][]Obligation {
+	result := make(map[ResponsibleRole][]Obligation)
+	for _, obl := range obligations {
+		result[obl.Responsible] = append(result[obl.Responsible], obl)
+	}
+	return result
+}
+
+// containsString checks if a slice contains a string
+func containsString(slice []string, s string) bool {
+	for _, item := range slice {
+		if item == s {
+			return true
+		}
+	}
+	return false
+}