feat: 添加预算统计服务增强和日志系统改进

1. 新增 BudgetStatsService：将预算统计逻辑从 BudgetService 中提取为独立服务，支持月度和年度统计，包含归档数据支持和硬性预算调整算法
2. 日志系统增强：添加请求ID追踪功能，支持通过请求ID查询关联日志，新增类名筛选功能
3. 日志解析优化：修复类名解析逻辑，正确提取 SourceContext 中的类名信息
4. 代码清理：移除不需要的方法名相关代码，简化日志筛选逻辑

WebApi/Middleware/RequestIdMiddleware.cs

@@ -0,0 +1,38 @@
+using Serilog.Context;
+
+namespace WebApi.Middleware;
+
+public class RequestIdMiddleware
+{
+    private readonly RequestDelegate _next;
+
+    public RequestIdMiddleware(RequestDelegate next)
+    {
+        _next = next;
+    }
+
+    public async Task InvokeAsync(HttpContext context)
+    {
+        var requestId = context.Request.Headers["X-Request-ID"].FirstOrDefault() ?? Guid.NewGuid().ToString("N");
+        
+        context.Items["RequestId"] = requestId;
+        
+        using (LogContext.PushProperty("RequestId", requestId))
+        {
+            await _next(context);
+        }
+    }
+}
+
+public static class RequestIdExtensions
+{
+    public static string? GetRequestId(this HttpContext context)
+    {
+        return context.Items["RequestId"] as string;
+    }
+    
+    public static IApplicationBuilder UseRequestId(this IApplicationBuilder builder)
+    {
+        return builder.UseMiddleware<RequestIdMiddleware>();
+    }
+}