refactor(JournalTaskConsumer): 优化AI评分prompt与图片加载逻辑

1. 新增无效作答固定返回文案常量
2. 调整prompt提示词，补充无效作答评分规则与返回要求
3. 移除冗余的参考答案无结果提示与题目基础信息打印
4. 封装图片流获取方法，兼容OSS和HTTP链接
5. 新增结果标准化处理，统一无效作答返回格式

QYZH.InteractiveMagazine.WorkService/Consumers/JournalTaskReceiveConsumer.cs

@@ -25,6 +25,7 @@ public class JournalTaskReceiveConsumer(
     private const long DefaultMaxImageBytes = 10 * 1024 * 1024;
     private const float DefaultCompletionThreshold = 80;
     private const float DefaultCommunityScoreThreshold = 90;
+    private const string InvalidAnswerResult = "作答内容不符合要求";
     private const string AiProcessingMessage = "AI批阅中，请稍后";
     private static readonly object AiSemaphoreLock = new();
     private static SemaphoreSlim? aiSemaphore;
@@ -359,7 +360,7 @@ public class JournalTaskReceiveConsumer(
         prompt.AppendLine(scoreUnit.Questions.Count > 1
             ? "这是同一跨页题目的多页作答，请综合全部学生作答图片评分。"
             : "这是单页题目作答，请根据学生作答图片评分。");
-        prompt.AppendLine("参考答案不是必有；若无参考答案，以题目 Prompt 和学生答案为准评分。");
+        prompt.AppendLine("以题目 Prompt 和学生答案为准评分,若有参考答案请结合参考答案。");
         if (referenceAnswerTexts.Count > 0)
         {
             prompt.AppendLine("参考答案文本：");
@@ -368,17 +369,10 @@ public class JournalTaskReceiveConsumer(
                 prompt.AppendLine($"{i + 1}. {referenceAnswerTexts[i]}");
             }
         }
-        else
-        {
-            prompt.AppendLine("参考答案文本：无");
-        }
         prompt.AppendLine();
         prompt.AppendLine("题目信息：");
         foreach (var context in scoreUnit.Questions)
         {
-            prompt.AppendLine($"- TaskId：{context.Task.Id}");
-            prompt.AppendLine($"  页码：{context.Page?.PageNum ?? 0}");
-            prompt.AppendLine($"  题号：{context.Task.No}");
             prompt.AppendLine($"  题目内容：{context.Task.Task}");
             prompt.AppendLine($"  评分Prompt：{context.Task.Prompt}");
             prompt.AppendLine($"  成长值上限：{context.Task.GrowthPoint}");
@@ -394,6 +388,8 @@ public class JournalTaskReceiveConsumer(
         prompt.AppendLine("- 看不清、缺页、无法识别或答案明显不完整时，降低 Completion，不要猜测高分。");
         prompt.AppendLine("- Completion 表示作答完整度，范围 0-100。");
         prompt.AppendLine("- Result 返回 50 字内中文评语。");
+        prompt.AppendLine("若作答内容与题目要求不符、答非所问、空白、仅抄题或无法形成有效答案，Score/GrowthPoint/Points/Comprehension/Judgment/Expression/Persuasiveness 均返回 0。");
+        prompt.AppendLine("若作答内容不符合要求，Result 必须且只能返回：作答内容不符合要求。不要补充原因、建议或其他文字。");
         prompt.AppendLine();
         prompt.AppendLine("只返回如下 JSON 字段：");
         prompt.AppendLine("{");
@@ -424,7 +420,7 @@ public class JournalTaskReceiveConsumer(
         {
             cancellationToken.ThrowIfCancellationRequested();
 
-            await using var imageStream = ossService.GetObjectStream(imageUrl);
+            await using var imageStream = await GetImageStreamAsync(imageUrl, cancellationToken);
             if (imageStream == null)
             {
                 throw new InvalidOperationException($"答案图片读取失败，TaskId: {question.Id}, Url: {imageUrl}");
@@ -474,7 +470,7 @@ public class JournalTaskReceiveConsumer(
 
             try
             {
-                await using var imageStream = ossService.GetObjectStream(imageUrl);
+                await using var imageStream = await GetImageStreamAsync(imageUrl, cancellationToken);
                 if (imageStream == null)
                 {
                     throw new InvalidOperationException($"参考答案图片读取失败，TaskId: {taskId}, Url: {imageUrl}");
@@ -590,6 +586,18 @@ public class JournalTaskReceiveConsumer(
         throw new InvalidOperationException($"AI评分调用失败，TaskId: {taskId}", lastException);
     }
 
+    private async Task<Stream?> GetImageStreamAsync(string imageUrl, CancellationToken cancellationToken)
+    {
+        if (Uri.TryCreate(imageUrl, UriKind.Absolute, out var uri)
+            && (uri.Scheme == Uri.UriSchemeHttp || uri.Scheme == Uri.UriSchemeHttps))
+        {
+            var httpClient = httpClientFactory.CreateClient();
+            return await httpClient.GetStreamAsync(uri, cancellationToken);
+        }
+
+        return ossService.GetObjectStream(imageUrl);
+    }
+
     private static bool ShouldRetry(System.Net.HttpStatusCode statusCode)
     {
         var status = (int)statusCode;
@@ -732,10 +740,22 @@ public class JournalTaskReceiveConsumer(
             Expression = Clamp(scoreResult.Expression, 0, task.Expression),
             Persuasiveness = Clamp(scoreResult.Persuasiveness, 0, task.Persuasiveness),
             Completion = Clamp(scoreResult.Completion, 0, 100),
-            Result = TrimResult(scoreResult.Result)
+            Result = NormalizeResult(scoreResult.Result)
         };
     }
 
+    private static string NormalizeResult(string? result)
+    {
+        var trimmedResult = TrimResult(result);
+        if (trimmedResult.Contains("不符合要求", StringComparison.Ordinal) ||
+            trimmedResult.Contains("不符", StringComparison.Ordinal))
+        {
+            return InvalidAnswerResult;
+        }
+
+        return trimmedResult;
+    }
+
     private static float Clamp(float value, float min, float max)
     {
         if (float.IsNaN(value) || float.IsInfinity(value))