fix: Build-Fehler — LegalContext Namenskollision + Registration Handler

- LegalContext → LegalDomainContext (Kollision mit legal_rag.go LegalContext)
- ExplainResponse.LegalContext bleibt unveraendert (RAG-Typ)
- Registration Handler: Intake ist struct, kein []byte
- Unbenutzten json Import entfernt

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

ai-compliance-sdk/internal/api/handlers/registration_handlers.go

@@ -1,7 +1,6 @@
 package handlers
 
 import (
-	"encoding/json"
 	"net/http"
 
 	"github.com/breakpilot/ai-compliance-sdk/internal/ucca"
@@ -173,13 +172,9 @@ func (h *RegistrationHandlers) Prefill(c *gin.Context) {
 		return
 	}
 
-	// Extract intake data
-	var intake ucca.UseCaseIntake
-	if assessment.Intake != nil {
-		json.Unmarshal(assessment.Intake, &intake)
-	}
+	// Pre-fill registration from assessment intake
+	intake := assessment.Intake
 
-	// Pre-fill registration from assessment
 	reg := ucca.AIRegistration{
 		TenantID:           tenantID,
 		SystemName:         intake.Title,