jiff for table definition added

common/proto/auth.proto

@@ -8,6 +8,7 @@ service AuthService {
   rpc Register(RegisterRequest) returns (AuthResponse);
   rpc Login(LoginRequest) returns (LoginResponse);
   rpc GetAuthorization(GetAuthorizationRequest) returns (AuthorizationSnapshot);
+  rpc SetTimezone(SetTimezoneRequest) returns (UserPreferences);
 }
 
 message RegisterRequest {
@@ -38,6 +39,15 @@ message LoginResponse {
   string role = 5; // User's role
   string username = 6;
   AuthorizationSnapshot authorization = 7;
+  string timezone = 8;
+}
+
+message SetTimezoneRequest {
+  string timezone = 1; // IANA timezone, for example Europe/Bratislava
+}
+
+message UserPreferences {
+  string timezone = 1;
 }
 
 message GetAuthorizationRequest {}