flameshot-once: make timeout configurable

krebs/5pkgs/simple/flameshot-once/profile.nix

@@ -77,6 +77,14 @@ let
           default = false;
           type = types.bool;
         };
+        timeout = mkOption {
+          default = 100;
+          description = ''
+            Maximum time in milliseconds allowed for the flameshot daemon to
+            react.
+          '';
+          type = types.positive;
+        };
       };
     };
   };
@@ -125,5 +133,6 @@ in
 
   pkgs.writeDash "flameshot.profile" ''
     export FLAMESHOT_CAPTURE_PATH=${cfg.savePath}
+    export FLAMESHOT_ONCE_TIMEOUT=${toString cfg.timeout}
     export XDG_CONFIG_HOME=${XDG_CONFIG_HOME}
   ''