fix helix and mpv modules

the helix wrapper wasn't working properly with spaced paths,
and mpv seems to not be configured to use /etc/mpv on nixos.

Now both of them work very similarly

cli/helix.nix

@@ -13,6 +13,8 @@ in
   options.nixowos.cli.${name} = {
     enable = lib.mkEnableOption name;
 
+    package = lib.mkPackageOption pkgs name { };
+
     extraConfig = lib.mkOption {
       type = lib.types.lines;
       default = /* toml */ ''
@@ -31,12 +33,19 @@ in
 
   config = lib.mkIf cfg.enable {
     environment.systemPackages = [
-      (pkgs.writeShellScriptBin "hx" "${pkgs.helix}/bin/hx -c /etc/${name}.toml $@")
+      (pkgs.symlinkJoin {
+        inherit name;
+        paths = [ cfg.package ];
+        nativeBuildInputs = [ pkgs.makeWrapper ];
+        postBuild = ''
+          wrapProgram $out/bin/hx \
+            --add-flags "-c" \
+            --add-flags "${pkgs.writeText "${name}.toml" cfg.extraConfig}"
+        '';
+      })
     ];
 
     # nixos/modules/programs/environment.nix uses mkDefault "nano"
     environment.variables.EDITOR = lib.mkOverride 900 "hx";
-
-    environment.etc."${name}.toml".text = cfg.extraConfig;
   };
 }

graphical/mpv.nix

@@ -32,7 +32,16 @@ in
   };
 
   config = lib.mkIf cfg.enable {
-    environment.systemPackages = [ cfg.package ];
-    environment.etc."${name}/${name}.conf".text = cfg.extraConfig;
+    environment.systemPackages = [
+      (pkgs.symlinkJoin {
+        inherit name;
+        paths = [ cfg.package ];
+        nativeBuildInputs = [ pkgs.makeWrapper ];
+        postBuild = ''
+          wrapProgram $out/bin/${name} \
+            --add-flags "--config-dir=${pkgs.writeTextDir "${name}.conf" cfg.extraConfig}"
+        '';
+      })
+    ];
   };
 }