added backend for user management

backend/src/models/Employee.ts

@@ -0,0 +1,39 @@
+// backend/src/models/Employee.ts
+export interface Employee {
+  id: string;
+  email: string;
+  password: string;
+  name: string;
+  role: 'admin' | 'instandhalter' | 'user';
+  isActive: boolean;
+  phone?: string;
+  department?: string;
+  createdAt: string;
+  lastLogin?: string;
+}
+
+export interface Availability {
+  id: string;
+  employeeId: string;
+  dayOfWeek: number;
+  startTime: string;
+  endTime: string;
+  isAvailable: boolean;
+}
+
+export interface CreateEmployeeRequest {
+  email: string;
+  password: string;
+  name: string;
+  role: 'admin' | 'instandhalter' | 'user';
+  phone?: string;
+  department?: string;
+}
+
+export interface UpdateEmployeeRequest {
+  name?: string;
+  role?: 'admin' | 'instandhalter' | 'user';
+  isActive?: boolean;
+  phone?: string;
+  department?: string;
+}