ci(backend): 调整 embed server

backend/Makefile

@@ -1,6 +1,16 @@
-.PHONY: wire
+.PHONY: wire build build-embed
 
 wire:
 	@echo "生成 Wire 代码..."
 	@cd cmd/server && go generate
-	@echo "Wire 代码生成完成"
+	@echo "Wire 代码生成完成"
+
+build:
+	@echo "构建后端（不嵌入前端）..."
+	@go build -o bin/server ./cmd/server
+	@echo "构建完成: bin/server"
+
+build-embed:
+	@echo "构建后端（嵌入前端）..."
+	@go build -tags embed -o bin/server ./cmd/server
+	@echo "构建完成: bin/server (with embedded frontend)"