refactor(ssh): unify SSH agent approach (use 'KeePassXC')

home/modules/keepassxc/default.nix

@@ -15,6 +15,7 @@ in
       enable = true;
       settings = {
         Browser.Enabled = true;
+        SSHAgent.Enabled = true;
       };
     };
   };

home/modules/ssh/default.nix

@@ -14,6 +14,13 @@ in
   config = lib.mkIf cfg.enable {
     home.packages = with pkgs; [ sshfs ];
 
+    services.ssh-agent.enable = true;
+
+    systemd.user.services.ssh-agent.Service.Environment = [
+      "SSH_ASKPASS=${pkgs.lxqt.lxqt-openssh-askpass}/bin/lxqt-openssh-askpass"
+      "SSH_ASKPASS_REQUIRE=prefer"
+    ];
+
     programs.ssh = {
       enable = true;
       enableDefaultConfig = false;