feat(cabana): add mltextarea field type

- mltextarea compiles (with size), binds as a writable scalar and goes
  through the mltext lift, translation write and hydrate paths
- preset on or from an mltextarea field stays refused
- tests: compile, Postgres round trip over a nullable host column with
  multi-line text, invalid locale maps, preset refusals

modules/cabana/crud.go

@@ -30,8 +30,8 @@ type CRUDService struct {
 	// commit; tr localizes the file limit messages. Both may be nil.
 	bucket *blob.Bucket
 	tr     *phrasebook.Translator
-	// writer persists non-default locale values for mltext/mlmarkdown fields.
-	// Nil when the translate plugin is not mounted.
+	// writer persists non-default locale values for mltext/mltextarea/mlmarkdown
+	// fields. Nil when the translate plugin is not mounted.
 	writer TranslationWriter
 }
 
@@ -1224,7 +1224,7 @@ func modelColumns(model any) map[string]struct{} {
 func scalarFormField(typ string) bool {
 	switch typ {
 	case "text", "textarea", "number", "checkbox", "switch", "dropdown", "datepicker",
-		"markdown", "mltext", "mlmarkdown":
+		"markdown", "mltext", "mltextarea", "mlmarkdown":
 		return true
 	default:
 		return false