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/base.nix

@@ -1,7 +1,6 @@
 {
   pkgs,
-  username,
-  userfullname,
+  myvars,
   nuenv,
   ...
 } @ args: {
@@ -50,8 +49,8 @@
     rsync
   ];
 
-  users.users.${username} = {
-    description = userfullname;
+  users.users.${myvars.username} = {
+    description = myvars.userfullname;
     # Public Keys that can be used to login to all my PCs, Macbooks, and servers.
     #
     # Since its authority is so large, we must strengthen its security:
@@ -78,7 +77,7 @@
     # given the users in this list the right to specify additional substituters via:
     #    1. `nixConfig.substituers` in `flake.nix`
     #    2. command line args `--options substituers http://xxx`
-    trusted-users = [username];
+    trusted-users = [myvars.username];
 
     # substituers that will be considered before the official ones(https://cache.nixos.org)
     substituters = [