feat(grpc): add auth service transport

proto/gapido_auth/generated/auth.proto

@@ -0,0 +1,63 @@
+syntax = "proto3";
+
+package gapido.auth.v1;
+
+service AuthService {
+  rpc RequestOtp (RequestOtpRequest) returns (RequestOtpResponse);
+  rpc VerifyOtp (VerifyOtpRequest) returns (TokenResponse);
+  rpc RefreshToken (RefreshTokenRequest) returns (TokenResponse);
+  rpc RevokeRefreshToken (RevokeRefreshTokenRequest) returns (RevokeRefreshTokenResponse);
+  rpc PublicPing (PingRequest) returns (PingResponse);
+  rpc UserOnly (ProtectedRequest) returns (ProtectedResponse);
+  rpc AdminOnly (ProtectedRequest) returns (ProtectedResponse);
+}
+
+message RequestOtpRequest {
+  string mobile = 1;
+  string purpose = 2;
+}
+
+message RequestOtpResponse {
+  bool accepted = 1;
+}
+
+message VerifyOtpRequest {
+  string mobile = 1;
+  string code = 2;
+  string purpose = 3;
+}
+
+message RefreshTokenRequest {
+  string refresh_token = 1;
+}
+
+message RevokeRefreshTokenRequest {
+  string refresh_token = 1;
+}
+
+message RevokeRefreshTokenResponse {
+  bool revoked = 1;
+}
+
+message TokenResponse {
+  string access_token = 1;
+  string refresh_token = 2;
+  string token_type = 3;
+  int32 expires_in = 4;
+  string role = 5;
+}
+
+message PingRequest {}
+
+message PingResponse {
+  string message = 1;
+}
+
+message ProtectedRequest {}
+
+message ProtectedResponse {
+  string user_id = 1;
+  string role = 2;
+  string message = 3;
+}
+