Merge pull request #280 from chouzz/fix/daily-statistics-id-null-261

fix(stats): assign Id for DailyStatistics on creation to prevent PK null (#261)

Author: 239573049

src/KoalaWiki/Services/StatisticsService.cs

@@ -1135,6 +1135,7 @@ public async Task<bool> GenerateDailyStatisticsAsync(DateTime? date = null)
                 // 创建新的统计数据
                 var dailyStats = new DailyStatistics
                 {
+                    Id = Guid.NewGuid().ToString(),
                     Date = targetDate,
                     NewUsersCount = newUsersCount,
                     NewRepositoriesCount = newRepositoriesCount,