nixos/orca: Fix systemd unit

The new systemd unit has `WantedBy=graphical-session.target`, and
`ExecStart=orca` needs to be patched to the absolute path.

nixos/modules/services/accessibility/orca.nix

@@ -21,6 +21,7 @@ in
   config = mkIf cfg.enable {
     environment.systemPackages = [ cfg.package ];
     systemd.packages = [ cfg.package ];
+    systemd.user.services.orca.wantedBy = [ "graphical-session.target" ];
     services.speechd.enable = true;
   };
 }

pkgs/by-name/or/orca/package.nix

@@ -104,6 +104,7 @@ python3.pkgs.buildPythonApplication rec {
 
   preFixup = ''
     makeWrapperArgs+=("''${gappsWrapperArgs[@]}")
+    substituteInPlace $out/lib/systemd/user/orca.service --replace-fail ExecStart=orca ExecStart=$out/bin/orca
   '';
 
   passthru = {