fix(定时轮): 初始化失败返回错误并补充单测

- NewTimingWheelService 改为返回 error，避免 panic

- ProvideTimingWheelService 透传 error 并更新 wire 生成代码

- 补充定时任务调度/取消/周期任务相关单元测试

backend/internal/service/timing_wheel_service.go

@@ -1,6 +1,7 @@
 package service
 
 import (
+	"fmt"
 	"log"
 	"sync"
 	"time"
@@ -8,6 +9,8 @@ import (
 	"github.com/zeromicro/go-zero/core/collection"
 )
 
+var newTimingWheel = collection.NewTimingWheel
+
 // TimingWheelService wraps go-zero's TimingWheel for task scheduling
 type TimingWheelService struct {
 	tw       *collection.TimingWheel
@@ -15,18 +18,18 @@ type TimingWheelService struct {
 }
 
 // NewTimingWheelService creates a new TimingWheelService instance
-func NewTimingWheelService() *TimingWheelService {
+func NewTimingWheelService() (*TimingWheelService, error) {
 	// 1 second tick, 3600 slots = supports up to 1 hour delay
 	// execute function: runs func() type tasks
-	tw, err := collection.NewTimingWheel(1*time.Second, 3600, func(key, value any) {
+	tw, err := newTimingWheel(1*time.Second, 3600, func(key, value any) {
 		if fn, ok := value.(func()); ok {
 			fn()
 		}
 	})
 	if err != nil {
-		panic(err)
+		return nil, fmt.Errorf("创建 timing wheel 失败: %w", err)
 	}
-	return &TimingWheelService{tw: tw}
+	return &TimingWheelService{tw: tw}, nil
 }
 
 // Start starts the timing wheel