fix: spread response data instead of nesting under 'data' key

The Phase 2.1 refactor wrapped success() responses as { success, data: {...} }
but the frontend expects flat responses like { success, license: {...} }.
This caused license to show FREE TIER and broke other API consumers.

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

dashcaddy-api/response-helpers.js

@@ -9,7 +9,7 @@ const { HTTP_STATUS } = require('./constants');
 function success(res, data, statusCode = HTTP_STATUS.OK) {
   return res.status(statusCode).json({
     success: true,
-    data
+    ...data
   });
 }
 
@@ -29,7 +29,7 @@ function successMessage(res, message, statusCode = HTTP_STATUS.OK) {
 function created(res, data) {
   return res.status(HTTP_STATUS.CREATED).json({
     success: true,
-    data
+    ...data
   });
 }