fix: access_token field, username vs name, auth response

PulseHealth/Models/AuthModels.swift

@@ -12,18 +12,30 @@ struct RegisterRequest: Codable {
 }
 
 struct AuthResponse: Codable {
-    let token: String
+    let token: String?
+    let accessToken: String?
     let user: UserInfo
+    
+    var authToken: String { token ?? accessToken ?? "" }
+    
+    enum CodingKeys: String, CodingKey {
+        case token
+        case accessToken = "access_token"
+        case user
+    }
 }
 
 struct UserInfo: Codable {
     let id: Int
     let email: String
     let name: String?
+    let username: String?
     let createdAt: String?
 
+    var displayName: String { username ?? name ?? email }
+
     enum CodingKeys: String, CodingKey {
-        case id, email, name
+        case id, email, name, username
         case createdAt = "created_at"
     }
 }