feat: Add continent and park type fields to Park and ParkLocation models; update API filters and documentation

docs/lib-api.ts

@@ -745,7 +745,6 @@ export const parksApi = {
       Object.entries(params).forEach(([key, value]) => {
         if (value !== undefined) {
           // Note: continent and park_type parameters are accepted but ignored by backend
-          // due to missing model fields (ParkLocation has no continent, Park has no park_type)
           searchParams.append(key, value.toString());
         }
       });