feat: UI全面改造 + 后端多项修复

【后端修复】
- 删除diet/consultation agent假工具声明
- 修复DayOfWeek实体注释
- 修复Vision API content序列化
- cleanup_service级联删除修复
- 用药提醒时区偏差修复
- 统一DateTime处理(UtcNow+8)
- 新增UTC DateTime JSON转换器

【前端UI重构】
- 配色体系全面更新(#8B5CF6淡紫+#F0ECFF背景)
- 登录页重设计
- 首页重设计(透明顶栏、渐变背景、胶囊输入区)
- 聊天卡片加白蓝边框、渐变标题
- 侧边栏重构(渐变背景、合并顶部、删除底部设置)
- 确认卡片可编辑字段恢复
- 所有子页面加返回按钮
- catch异常加日志
- 删除后refresh provider缓存

backend/src/Health.WebApi/Endpoints/ai_chat_endpoints.cs

@@ -291,7 +291,7 @@ public static class AiChatEndpoints
                     var result = response.Choices?.FirstOrDefault()?.Message?.Content ?? "{}";
                     // 记录VLM原始返回用于排查
                     var uploadsDir2 = Path.Combine(Directory.GetCurrentDirectory(), "uploads");
-                    var logPath = Path.Combine(uploadsDir2, $"vlm_log_{DateTime.Now:HHmmss}.txt");
+                    var logPath = Path.Combine(uploadsDir2, $"vlm_log_{DateTime.UtcNow:HHmmss}.txt");
                     await File.WriteAllTextAsync(logPath, $"MODEL: {Environment.GetEnvironmentVariable("VLM_MODEL")}\nIMAGE_SIZE: {imageUrls.FirstOrDefault()?.Length ?? 0}\nRESPONSE:\n{result}", ct);
                     return Results.Ok(new { code = 0, data = result, message = (string?)null });
                 }
@@ -340,7 +340,6 @@ public static class AiChatEndpoints
         AgentType.Unified => [
             HealthDataAgentHandler.RecordHealthDataTool,
             CommonAgentHandler.QueryHealthRecordsTool,
-            DietAgentHandler.EstimateFoodTool,
             MedicationAgentHandler.ManageMedicationTool,
             ExerciseAgentHandler.ManageExerciseTool,
             CommonAgentHandler.CheckArchiveTool,
@@ -359,13 +358,11 @@ public static class AiChatEndpoints
             "query_health_records" => CommonAgentHandler.Execute(toolName, root, db, userId),
             "check_archive" => CommonAgentHandler.Execute(toolName, root, db, userId),
             "manage_medication" => MedicationAgentHandler.Execute(toolName, root, db, userId),
-            "estimate_food_text" => DietAgentHandler.Execute(toolName, root, db, userId),
             "analyze_report" => visionClient != null
                 ? ReportAgentHandler.AnalyzeReport(db, userId, root, visionClient)
                 : Task.FromResult<object>(new { success = false, message = "VLM服务未配置" }),
             "manage_exercise" => ExerciseAgentHandler.Execute(toolName, root, db, userId),
             "manage_archive" => CommonAgentHandler.ExecuteManageArchive(db, userId, root),
-            "request_doctor" => ConsultationAgentHandler.Execute(toolName, root, db, userId),
             _ => Task.FromResult<object>(new { success = false, message = $"未知工具: {toolName}" })
         };
     }
@@ -470,9 +467,6 @@ public static class AiChatEndpoints
                     metadata["recordTime"] = DateTime.UtcNow.AddHours(8).ToString("MM月dd日 HH:mm");
                 }
                 break;
-            case "estimate_food_text":
-                messageType = "diet_analysis";
-                break;
             case "analyze_report":
                 messageType = "report_analysis";
                 break;