feat(proto): add separate client/user-agent gRPC services

protobufs/auth.proto

@@ -5,23 +5,37 @@ package arbiter.auth;
 import "google/protobuf/timestamp.proto";
 
 message AuthChallengeRequest {
-    bytes pubkey = 1;
+  bytes pubkey = 1;
 }
 
 message AuthChallenge {
-    bytes pubkey = 1;
-    bytes nonce = 2;
-    google.protobuf.Timestamp minted = 3 ; 
+  bytes pubkey = 1;
+  bytes nonce = 2;
+  google.protobuf.Timestamp minted = 3;
 }
 
 message AuthChallengeSolution {
-    AuthChallenge challenge = 1 ;
-    bytes signature = 2;
+  AuthChallenge challenge = 1;
+  bytes signature = 2;
 }
 
 message AuthResponse {
-    string token = 1;
-    string refresh_token = 2;
-    google.protobuf.Timestamp expires_at = 3 ;
-    google.protobuf.Timestamp refresh_expires_at = 4 ;
-}
+  string token = 1;
+  string refresh_token = 2;
+  google.protobuf.Timestamp expires_at = 3;
+  google.protobuf.Timestamp refresh_expires_at = 4;
+}
+
+message ClientMessage {
+  oneof payload {
+    AuthChallengeRequest auth_challenge_request = 1;
+    AuthChallengeSolution auth_challenge_solution = 2;
+  }
+}
+
+message ServerMessage {
+  oneof payload {
+    AuthChallenge auth_challenge = 1;
+    AuthResponse auth_response = 2;
+  }
+}