feat(domains): ✨ add domain support for DrawDB integration

- Introduce Domain and DomainTable models for logical grouping of tables.
- Implement export and import functionality for domains in DrawDB format.
- Update template execution modes to include domain processing.
- Enhance documentation for domain features and usage.

pkg/writers/drawdb/writer.go

@@ -127,6 +127,51 @@ func (w *Writer) databaseToDrawDB(d *models.Database) *DrawDBSchema {
 		}
 	}
 
+	// Create subject areas for domains
+	for domainIdx, domainModel := range d.Domains {
+		// Calculate bounds for all tables in this domain
+		minX, minY := 999999, 999999
+		maxX, maxY := 0, 0
+
+		domainTableCount := 0
+		for _, domainTable := range domainModel.Tables {
+			// Find the table in the schema to get its position
+			for _, t := range schema.Tables {
+				if t.Name == domainTable.TableName {
+					if t.X < minX {
+						minX = t.X
+					}
+					if t.Y < minY {
+						minY = t.Y
+					}
+					if t.X+colWidth > maxX {
+						maxX = t.X + colWidth
+					}
+					if t.Y+rowHeight > maxY {
+						maxY = t.Y + rowHeight
+					}
+					domainTableCount++
+					break
+				}
+			}
+		}
+
+		// Only create area if domain has tables in this schema
+		if domainTableCount > 0 {
+			area := &DrawDBArea{
+				ID:     areaID,
+				Name:   domainModel.Name,
+				Color:  getColorForIndex(len(d.Schemas) + domainIdx), // Use different colors than schemas
+				X:      minX - 20,
+				Y:      minY - 20,
+				Width:  maxX - minX + 40,
+				Height: maxY - minY + 40,
+			}
+			schema.SubjectAreas = append(schema.SubjectAreas, area)
+			areaID++
+		}
+	}
+
 	// Add relationships
 	for _, schemaModel := range d.Schemas {
 		for _, table := range schemaModel.Tables {