fix: VLM识别修复 + 饮食CRUD + 侧边栏美化 + UI优化

- VLM: ChatMessage.Content string→object, 修复视觉content双重序列化
- 饮食: diet/medication端点 record→手动JSON解析, 修复循环引用
- 饮食记录: 左滑删除 + 去评分 + AI饮食评语(DeepSeek)
- 侧边栏: 功能区统一Row+Expanded, 服务包compact模式
- 历史对话: 点击加载历史消息
- 登录页: 居中布局, 去底部空白
- UI: 主色加深#6C5CE7, maxWidth:1024防图片超大

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

@@ -12,21 +12,46 @@ public static class DietEndpoints
             var query = db.DietRecords.Include(d => d.FoodItems).Where(d => d.UserId == userId);
             if (DateOnly.TryParse(date, out var d)) query = query.Where(r => r.RecordedAt == d);
             if (Enum.TryParse<MealType>(mealType, ignoreCase: true, out var mt)) query = query.Where(r => r.MealType == mt);
-            var records = await query.OrderByDescending(r => r.RecordedAt).ToListAsync(ct);
+            var records = await query.OrderByDescending(r => r.RecordedAt).Select(r => new
+            {
+                r.Id, MealType = r.MealType.ToString(), r.TotalCalories, r.HealthScore, r.RecordedAt,
+                foodItems = r.FoodItems.Select(f => new { f.Name, f.Portion, f.Calories })
+            }).ToListAsync(ct);
             return Results.Ok(new { code = 0, data = records, message = (string?)null });
         });
 
-        group.MapPost("/", async (CreateDietRequest req, HttpContext http, AppDbContext db, CancellationToken ct) =>
+        group.MapPost("/", async (HttpRequest request, HttpContext http, AppDbContext db, CancellationToken ct) =>
         {
             var userId = GetUserId(http);
+            request.EnableBuffering();
+            using var reader = new StreamReader(request.Body);
+            var body = await reader.ReadToEndAsync(ct);
+            request.Body.Position = 0;
+            using var json = JsonDocument.Parse(body);
+            var root = json.RootElement;
             var record = new DietRecord
             {
-                Id = Guid.NewGuid(), UserId = userId, MealType = req.MealType,
-                TotalCalories = req.TotalCalories, HealthScore = req.HealthScore, RecordedAt = req.RecordedAt ?? DateOnly.FromDateTime(DateTime.Now),
+                Id = Guid.NewGuid(), UserId = userId,
+                MealType = Enum.TryParse<MealType>(root.TryGetProperty("mealType", out var mt) ? mt.GetString() : "Lunch", out var meal) ? meal : MealType.Lunch,
+                TotalCalories = root.TryGetProperty("totalCalories", out var tc) ? tc.GetInt32() : null,
+                HealthScore = root.TryGetProperty("healthScore", out var hs) ? hs.GetInt32() : null,
+                RecordedAt = root.TryGetProperty("recordedAt", out var ra) && DateOnly.TryParse(ra.GetString(), out var d) ? d : DateOnly.FromDateTime(DateTime.Now),
             };
-            if (req.FoodItems != null)
-                foreach (var fi in req.FoodItems)
-                    record.FoodItems.Add(new DietFoodItem { Id = Guid.NewGuid(), Name = fi.Name, Portion = fi.Portion, Calories = fi.Calories, ProteinGrams = fi.ProteinGrams, CarbsGrams = fi.CarbsGrams, FatGrams = fi.FatGrams, Warning = fi.Warning, SortOrder = fi.SortOrder });
+            if (root.TryGetProperty("foodItems", out var items))
+            {
+                var i = 0;
+                foreach (var fi in items.EnumerateArray())
+                {
+                    record.FoodItems.Add(new DietFoodItem
+                    {
+                        Id = Guid.NewGuid(), Name = fi.TryGetProperty("name", out var n) ? n.GetString()! : "",
+                        Portion = fi.TryGetProperty("portion", out var p) ? p.GetString() : null,
+                        Calories = fi.TryGetProperty("calories", out var c) ? c.GetInt32() : null,
+                        SortOrder = fi.TryGetProperty("sortOrder", out var so) ? so.GetInt32() : i,
+                    });
+                    i++;
+                }
+            }
             db.DietRecords.Add(record);
             await db.SaveChangesAsync(ct);
             return Results.Ok(new { code = 0, data = new { record.Id }, message = (string?)null });
@@ -45,5 +70,3 @@ public static class DietEndpoints
         Guid.TryParse(http.User.FindFirst(System.Security.Claims.ClaimTypes.NameIdentifier)?.Value, out var id) ? id : Guid.Empty;
 }
 
-public sealed record CreateDietRequest(MealType MealType, int? TotalCalories, int? HealthScore, DateOnly? RecordedAt, List<FoodItemDto>? FoodItems);
-public sealed record FoodItemDto(string Name, string? Portion, int? Calories, decimal? ProteinGrams, decimal? CarbsGrams, decimal? FatGrams, string? Warning, int SortOrder);