feat: custom content type icons, built-in types, user lookup

internal/infrastructure/persistence/models/contentTypeModel.go

@@ -6,6 +6,7 @@ type ContentType struct {
 	ID        uint32    `gorm:"primaryKey;autoIncrement"`
 	Key       string    `gorm:"column:type_key;size:40;not null;uniqueIndex"`
 	Name      string    `gorm:"size:100;not null"`
+	Icon      *string   `gorm:"size:40"`
 	Fields    string    `gorm:"type:text;not null"`
 	CreatedAt time.Time `gorm:"autoCreateTime"`
 	UpdatedAt time.Time `gorm:"autoUpdateTime"`