feat: GRPC method register agent

api/proto/homeops/hub.proto

@@ -6,8 +6,21 @@ option go_package = "github.com/lorsanstand/HomeOps-Hub/api/gen/homeops;homeops"
 
 service Hub {
   rpc Ping (google.protobuf.Empty) returns (PongResponse) {}
+  rpc RegisterAgent (RegisterAgentRequest) returns (RegisterAgentResponse) {}
 }
 
 message PongResponse {
   string pong = 1;
+}
+
+message RegisterAgentRequest {
+  string agent_id = 1;
+  string agent_name = 2;
+  string hostname = 3;
+  string version = 4;
+  string arch = 5;
+}
+
+message RegisterAgentResponse {
+  int64 heartbeat_interval_second = 1;
 }