chore: 补充后端核心模块的中文注释

backend/cmd/worker/main.go

@@ -17,8 +17,8 @@ import (
 	"syscall"
 	"time"
 
-	amqp "github.com/rabbitmq/amqp091-go"
 	"github.com/joho/godotenv"
+	amqp "github.com/rabbitmq/amqp091-go"
 	"gorm.io/gorm"
 )
 
@@ -40,6 +40,7 @@ const (
 	popularityBindingKey = "video.popularity.*"
 )
 
+// 带重试机制的基础设施连接函数
 func connectWithRetry(name string, maxRetries int, fn func() error) {
 	for i := 0; i < maxRetries; i++ {
 		if err := fn(); err == nil {
@@ -55,7 +56,7 @@ func connectWithRetry(name string, maxRetries int, fn func() error) {
 	log.Fatalf("%s: 超过最大重试次数", name)
 }
 
-// runWorkerWithRetry 为每个 Worker 创建独立 Channel，断开后自动重连
+// runWorkerWithRetry 为每个 Worker 创建独立 Channel 并设置 QoS，断开后自动重连
 func runWorkerWithRetry(ctx context.Context, name string, conn *amqp.Connection, fn func(*amqp.Channel) error) {
 	for {
 		select {