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(`-`).

hosts/idols-ruby/exporters/default.nix

@@ -0,0 +1,3 @@
+{mylib, ...}: {
+  imports = mylib.scanPaths ./.;
+}

hosts/idols-ruby/exporters/pve.nix

@@ -0,0 +1,4 @@
+{
+  # TODO
+  # https://github.com/NixOS/nixpkgs/blob/nixos-23.11/nixos/modules/services/monitoring/prometheus/exporters/pve.nix
+}