fix: use single-line ExecStart string for systemd compat

The indented string ('''...''') included newlines + spaces in the systemd
unit file, which systemd rejected with 'expected entry key name but got /'.
Use a plain double-quoted string instead so ExecStart stays on one line.

.gitignore

@@ -0,0 +1 @@
+.worktrees/

modules/home-manager/ntfy-notify/default.nix

@@ -80,9 +80,7 @@ in
       };
       Service = {
         Type = "simple";
-        ExecStart = ''
-          ${pkgs.ntfy-sh}/bin/ntfy subscribe
-        '';
+        ExecStart = "${pkgs.ntfy-sh}/bin/ntfy subscribe";
         Restart = "on-failure";
         RestartSec = 10;
       };