refactor: remove clients, invoice, and nuage module integrations

Strips out built-in clients, invoice, and nuage modules from core
handlers, module initializers, and action registries. This cleans up
hardcoded module dependencies, leaving only the posts module as a
reference implementation for the modular architecture.

src/modules/modules.actions.js

@@ -17,59 +17,13 @@
  * ```
  */
 
-// Import module actions (use relative paths for build compatibility)
-import {
-  isStripeEnabled,
-  isInteracEnabled,
-  getInteracEmail,
-  getPublicPageConfig,
-  getInvoiceByTokenAction,
-  createStripeCheckoutSessionAction,
-  generateInvoicePDFAction,
-  getInteracCredentialsAction,
-  generateReceiptPDFAction,
-} from './invoice/actions.js';
-
-import {
-  getShareByTokenAction,
-  verifySharePasswordAction,
-  getSharedContentsAction,
-  getShareFileDownloadUrlAction,
-  uploadToShareAction,
-  getPublicPageConfig as getNuagePublicPageConfig,
-} from './nuage/actions.js';
-
-// Import dashboard stats actions
-import { getInvoiceDashboardStats } from './invoice/dashboard/statsActions.js';
-
 // Register module actions (for public pages)
 export const MODULE_ACTIONS = {
-  invoice: {
-    isStripeEnabled,
-    isInteracEnabled,
-    getInteracEmail,
-    getPublicPageConfig,
-    getInvoiceByTokenAction,
-    createStripeCheckoutSessionAction,
-    generateInvoicePDFAction,
-    getInteracCredentialsAction,
-    generateReceiptPDFAction,
-  },
   posts: {},
-  nuage: {
-    getPublicPageConfig: getNuagePublicPageConfig,
-    getShareByTokenAction,
-    verifySharePasswordAction,
-    getSharedContentsAction,
-    getShareFileDownloadUrlAction,
-    uploadToShareAction,
-  },
 };
 
 // Register dashboard stats actions (for admin dashboard)
-export const MODULE_DASHBOARD_ACTIONS = {
-  invoice: getInvoiceDashboardStats,
-};
+export const MODULE_DASHBOARD_ACTIONS = {};
 
 /**
  * Get actions for a specific module