Don't export the theme schema

Knip flags it as unused outside the module.

Author: jplhomer

packages/app/src/cli/models/extensions/specifications/theme.ts

@@ -79,7 +79,7 @@ const ThemeCapabilitiesSchema = CapabilitiesSchema.extend({
   ),
 })
 
-export const ThemeSchema = BaseSchema.extend({
+const ThemeSchema = BaseSchema.extend({
   capabilities: ThemeCapabilitiesSchema.optional(),
 })