修正 update

Makefile

@@ -1,3 +1,5 @@
+export host=main
+
 # 运行本地开发环境(使用SSH隧道代理端口)
 dev:
 	@if ! go list -m github.com/air-verse/air@latest >/dev/null 2>&1; then \
@@ -19,12 +21,11 @@ build:
 
 # 更新部署到服务器
 update: build
-	host=main
-	ssh $host "mv ~/webp/main ~/webp/main_old"
-	scp dist/main $host:~/webp/main
+	ssh $(host) "mv ~/webp/main ~/webp/main_old"
+	scp dist/main $(host):~/webp/main
 	rm -rf dist
-	ssh $host "systemctl restart webp"
-	ssh $host "rm ~/webp/main_old"
+	ssh $(host) "systemctl restart webp"
+	ssh $(host) "rm ~/webp/main_old"
 
 # 设为系统服务和设置日志轮转
 service: