添加智能分类功能，支持获取未分类账单数量和列表；实现AI分类逻辑；更新相关API和前端视图

Service/EmailBackgroundService.cs

@@ -197,8 +197,12 @@ public class EmailBackgroundService(
                                     message.TextBody ?? message.HtmlBody ?? string.Empty
                                 ))
                             {
+                                #if DEBUG
+                                logger.LogDebug("DEBUG 模式下，跳过标记已读步骤");
+                                #else
                                 // 标记邮件为已读
                                 await emailFetchService.MarkAsReadAsync(uid);    
+                                #endif
                             }
                         }
                         catch (Exception ex)

Service/OpenAiService.cs

@@ -5,6 +5,7 @@ namespace Service;
 public interface IOpenAiService
 {
     Task<string?> ChatAsync(string systemPrompt, string userPrompt);
+    IAsyncEnumerable<string> ChatStreamAsync(string systemPrompt, string userPrompt);
 }
 
 public class OpenAiService(
@@ -68,4 +69,79 @@ public class OpenAiService(
             throw;
         }
     }
+
+    public async IAsyncEnumerable<string> ChatStreamAsync(string systemPrompt, string userPrompt)
+    {
+        var cfg = aiSettings.Value;
+        if (string.IsNullOrWhiteSpace(cfg.Endpoint) || 
+            string.IsNullOrWhiteSpace(cfg.Key) || 
+            string.IsNullOrWhiteSpace(cfg.Model))
+        {
+            logger.LogWarning("未配置 OpenAI/DeepSeek 接口，无法调用 AI");
+            yield break;
+        }
+
+        using var http = new HttpClient();
+        http.Timeout = TimeSpan.FromMinutes(5);
+        http.DefaultRequestHeaders.Authorization = new AuthenticationHeaderValue("Bearer", cfg.Key);
+
+        var payload = new
+        {
+            model = cfg.Model,
+            temperature = 0,
+            stream = true,
+            messages = new object[]
+            {
+                new { role = "system", content = systemPrompt },
+                new { role = "user", content = userPrompt }
+            }
+        };
+
+        var url = cfg.Endpoint.TrimEnd('/') + "/chat/completions";
+        var json = JsonSerializer.Serialize(payload);
+        using var content = new StringContent(json, Encoding.UTF8, "application/json");
+        
+        // 使用 SendAsync 来支持 HttpCompletionOption
+        using var request = new HttpRequestMessage(HttpMethod.Post, url)
+        {
+            Content = content
+        };
+        using var resp = await http.SendAsync(request, HttpCompletionOption.ResponseHeadersRead);
+        
+        if (!resp.IsSuccessStatusCode)
+        {
+            var err = await resp.Content.ReadAsStringAsync();
+            throw new InvalidOperationException($"AI接口调用失败: {(int)resp.StatusCode} {resp.ReasonPhrase}, {err}");
+        }
+
+        using var stream = await resp.Content.ReadAsStreamAsync();
+        using var reader = new StreamReader(stream);
+
+        string? line;
+        while ((line = await reader.ReadLineAsync()) != null)
+        {
+            if (string.IsNullOrWhiteSpace(line) || !line.StartsWith("data: "))
+                continue;
+
+            var data = line.Substring(6).Trim();
+            if (data == "[DONE]")
+                break;
+
+            // 解析JSON时不使用try-catch，因为在async iterator中不能使用
+            using var doc = JsonDocument.Parse(data);
+            var root = doc.RootElement;
+            if (root.TryGetProperty("choices", out var choices) && choices.GetArrayLength() > 0)
+            {
+                var delta = choices[0].GetProperty("delta");
+                if (delta.TryGetProperty("content", out var contentProp))
+                {
+                    var contentText = contentProp.GetString();
+                    if (!string.IsNullOrEmpty(contentText))
+                    {
+                        yield return contentText;
+                    }
+                }
+            }
+        }
+    }
 }