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/preset_ml_test.go

@@ -127,6 +127,32 @@ func TestPresetML(t *testing.T) {
 `,
 			checkErr: "field slug: preset field body must be a text or mltext field",
 		},
+		{
+			name: "mltextarea target is refused",
+			yaml: `fields:
+    title:
+        type: mltext
+        label: Title
+    excerpt:
+        type: mltextarea
+        label: Excerpt
+        preset: title
+`,
+			compileErr: "preset is only valid on type: text or mltext",
+		},
+		{
+			name: "mltextarea source is refused",
+			yaml: `fields:
+    excerpt:
+        type: mltextarea
+        label: Excerpt
+    slug:
+        type: mltext
+        label: Slug
+        preset: excerpt
+`,
+			checkErr: "field slug: preset field excerpt must be a text or mltext field",
+		},
 	}
 	for _, tc := range cases {
 		t.Run(tc.name, func(t *testing.T) {