feat: 实现公共工具包，包括日志、错误处理、数据库和缓存

backend/shared/proto/common/common.proto

@@ -0,0 +1,55 @@
+syntax = "proto3";
+
+package common;
+
+// 通用响应结构
+message Response {
+  int32 code = 1;
+  string message = 2;
+  bytes data = 3;
+}
+
+// 分页请求
+message PaginationRequest {
+  int32 page = 1;
+  int32 page_size = 2;
+}
+
+// 分页响应
+message PaginationResponse {
+  int32 total = 1;
+  int32 page = 2;
+  int32 page_size = 3;
+  int32 total_pages = 4;
+}
+
+// 错误信息
+message Error {
+  int32 code = 1;
+  string message = 2;
+  string details = 3;
+}
+
+// 空请求
+message EmptyRequest {
+}
+
+// 空响应
+message EmptyResponse {
+}
+
+// ID 请求
+message IDRequest {
+  string id = 1;
+}
+
+// ID 响应
+message IDResponse {
+  string id = 1;
+}
+
+// 状态响应
+message StatusResponse {
+  bool success = 1;
+  string message = 2;
+}