feat: c++ pragma 방식 => protocol buffer로 직렬화 수정 및 클라이언트 python gui 앱으로 변경

proto/Protocol.proto

@@ -0,0 +1,31 @@
+syntax = "proto3";
+
+package Protocol;
+
+message CS_Login {
+    string nickname = 1;
+}
+
+message SC_LoginResult {
+    bool success = 1;
+}
+
+message SC_UpgradeResult {
+    uint32 result = 1;
+    uint32 current_level = 2;
+    uint64 current_gold = 3;
+}
+
+message SC_SellResult {
+    uint64 earned_gold = 1;
+    uint64 total_gold = 2;
+}
+
+message RankingEntry {
+    string nickname = 1;
+    uint32 level = 2;
+}
+
+message SC_RankingList {
+    repeated RankingEntry entries = 1;
+}