feat(models): 🎉 Add GUID field to various models

* Introduced GUID field to Database, Domain, DomainTable, Schema, Table, View, Sequence, Column, Index, Relationship, Constraint, Enum, and Script models.
* Updated initialization functions to assign new GUIDs using uuid package.
* Enhanced DCTX reader and writer to utilize GUIDs from models where available.

pkg/writers/dctx/writer.go

@@ -133,7 +133,11 @@ func (w *Writer) mapTableFields(table *models.Table) models.DCTXTable {
 		prefix = table.Name[:3]
 	}
 
-	tableGuid := w.newGUID()
+	// Use GUID from model if available, otherwise generate a new one
+	tableGuid := table.GUID
+	if tableGuid == "" {
+		tableGuid = w.newGUID()
+	}
 	w.tableGuidMap[table.Name] = tableGuid
 
 	dctxTable := models.DCTXTable{
@@ -171,7 +175,11 @@ func (w *Writer) mapTableKeys(table *models.Table) []models.DCTXKey {
 }
 
 func (w *Writer) mapField(column *models.Column) models.DCTXField {
-	guid := w.newGUID()
+	// Use GUID from model if available, otherwise generate a new one
+	guid := column.GUID
+	if guid == "" {
+		guid = w.newGUID()
+	}
 	fieldKey := fmt.Sprintf("%s.%s", column.Table, column.Name)
 	w.fieldGuidMap[fieldKey] = guid
 
@@ -209,7 +217,11 @@ func (w *Writer) mapDataType(dataType string) string {
 }
 
 func (w *Writer) mapKey(index *models.Index, table *models.Table) models.DCTXKey {
-	guid := w.newGUID()
+	// Use GUID from model if available, otherwise generate a new one
+	guid := index.GUID
+	if guid == "" {
+		guid = w.newGUID()
+	}
 	keyKey := fmt.Sprintf("%s.%s", table.Name, index.Name)
 	w.keyGuidMap[keyKey] = guid
 
@@ -344,7 +356,7 @@ func (w *Writer) mapRelation(rel *models.Relationship, schema *models.Schema) mo
 	}
 
 	return models.DCTXRelation{
-		Guid:            w.newGUID(),
+		Guid:            rel.GUID,                      // Use GUID from relationship model
 		PrimaryTable:    w.tableGuidMap[rel.ToTable],   // GUID of the 'to' table (e.g., users)
 		ForeignTable:    w.tableGuidMap[rel.FromTable], // GUID of the 'from' table (e.g., posts)
 		PrimaryKey:      primaryKeyGUID,