fix a bug

ios/OralTrainer/Services/ImitationAssessor.swift

@@ -171,15 +171,19 @@ enum ImitationAssessor {
         }
         body.append(Data("--\(boundary)--\r\n".utf8))
 
+        var headers = [
+            "Accept": "application/json",
+            "Content-Type": "multipart/form-data; boundary=\(boundary)",
+        ]
+        if !AppConfig.authToken.isEmpty {
+            headers["Authorization"] = "Bearer \(AppConfig.authToken)"
+        }
         let result = try await HTTPClient.execute(
             baseURL: AppConfig.serverBaseURL,
             path: "api/v1/dub-shares",
             method: "POST",
             timeout: 120,
-            headers: [
-                "Accept": "application/json",
-                "Content-Type": "multipart/form-data; boundary=\(boundary)",
-            ],
+            headers: headers,
             body: body
         )
         guard (200...299).contains(result.statusCode) else {