feat: 实现注册优惠码功能

- 支持创建/编辑/删除优惠码，设置赠送金额和使用限制
  - 注册页面实时验证优惠码并显示赠送金额
  - 支持 URL 参数自动填充 (?promo=CODE)
  - 添加优惠码验证接口速率限制
  - 使用数据库行锁防止并发超限
  - 新增后台优惠码管理页面，支持复制注册链接

backend/internal/server/http.go

@@ -13,6 +13,7 @@ import (
 
 	"github.com/gin-gonic/gin"
 	"github.com/google/wire"
+	"github.com/redis/go-redis/v9"
 )
 
 // ProviderSet 提供服务器层的依赖
@@ -30,6 +31,7 @@ func ProvideRouter(
 	apiKeyAuth middleware2.APIKeyAuthMiddleware,
 	apiKeyService *service.APIKeyService,
 	subscriptionService *service.SubscriptionService,
+	redisClient *redis.Client,
 ) *gin.Engine {
 	if cfg.Server.Mode == "release" {
 		gin.SetMode(gin.ReleaseMode)
@@ -47,7 +49,7 @@ func ProvideRouter(
 		}
 	}
 
-	return SetupRouter(r, handlers, jwtAuth, adminAuth, apiKeyAuth, apiKeyService, subscriptionService, cfg)
+	return SetupRouter(r, handlers, jwtAuth, adminAuth, apiKeyAuth, apiKeyService, subscriptionService, cfg, redisClient)
 }
 
 // ProvideHTTPServer 提供 HTTP 服务器