fix(preload): whitelist word-template IPC channels, drop orphaned set-custom-start-page

tests/preload.test.js

@@ -44,7 +44,6 @@ describe('Preload Security', () => {
       'clear-header-footer-logo',
       'get-page-settings',
       'update-page-settings',
-      'set-custom-start-page',
       'process-pdf-operation',
       'get-pdf-page-count',
       'select-pdf-folder',

tests/setup.js

@@ -55,7 +55,6 @@ global.window.electronAPI = {
   page: {
     getSettings: jest.fn(),
     updateSettings: jest.fn(),
-    setCustomStartPage: jest.fn(),
   },
   pdf: {
     processOperation: jest.fn(),