refactor: Use haumea for filesystem-based module system for flake outputs

refactor: Use hyphen(`-`) for variable names & folder names(except Python), replace all unserscore(`_`) with hyphen(`-`).

modules/nixos/desktop.nix

@@ -2,7 +2,7 @@
   pkgs,
   config,
   lib,
-  username,
+  myvars,
   ...
 }:
 with lib; let
@@ -46,7 +46,7 @@ in {
           settings = {
             default_session = {
               # Wayland Desktop Manager is installed only for user ryan via home-manager!
-              user = username;
+              user = myvars.username;
               # .wayland-session is a script generated by home-manager, which links to the current wayland compositor(sway/hyprland or others).
               # with such a vendor-no-locking script, we can switch to another wayland compositor without modifying greetd's config here.
               command = "$HOME/.wayland-session"; # start a wayland session directly without a login manager
@@ -75,7 +75,7 @@ in {
             lightdm.enable = true;
             autoLogin = {
               enable = true;
-              user = username;
+              user = myvars.username;
             };
             # use a fake session to skip desktop manager
             # and let Home Manager take care of the X session