Add multi-user backend infrastructure: User model, management service and API

Co-authored-by: whyour <22700758+whyour@users.noreply.github.com>

back/types/express.d.ts

@@ -6,6 +6,11 @@ declare global {
   namespace Express {
     interface Request {
       platform: 'desktop' | 'mobile';
+      user?: {
+        userId?: number;
+        role?: number;
+      };
+      auth?: any;
     }
   }
 }