feat: implement authentication with JWT and user management

frontend/src/app/model/User.ts

@@ -1,5 +1,6 @@
 export interface User {
-  authentikId: string;
+  id: number;
+  email: string;
   username: string;
   balance: number;
 }

frontend/src/app/model/auth/AuthResponse.ts

@@ -0,0 +1,4 @@
+export interface AuthResponse {
+  token: string;
+  tokenType: string;
+}

frontend/src/app/model/auth/LoginRequest.ts

@@ -0,0 +1,4 @@
+export interface LoginRequest {
+  usernameOrEmail: string;
+  password: string;
+}

frontend/src/app/model/auth/RegisterRequest.ts

@@ -0,0 +1,5 @@
+export interface RegisterRequest {
+  email: string;
+  username: string;
+  password: string;
+}