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-kana/homepage/default.nix

@@ -0,0 +1,25 @@
+{pkgs, ...}: let
+  configDir = "/var/lib/homepage-dashboard";
+in {
+  # https://github.com/NixOS/nixpkgs/blob/nixos-unstable/nixos/modules/services/misc/homepage-dashboard.nix
+  services.homepage-dashboard = {
+    enable = true;
+    listenPort = 8082;
+    openFirewall = false;
+  };
+  systemd.services.homepage-dashboard.environment = {
+    HOMEPAGE_CONFIG_DIR = configDir;
+
+    # 1. The value of env var HOMEPAGE_VAR_XXX will replace {{HOMEPAGE_VAR_XXX}} in any config
+    # HOMEPAGE_VAR_XXX_APIKEY = "myapikey";
+    # 2. The value of env var HOMEPAGE_FILE_XXX must be a file path,
+    # the contents of which will be used to replace {{HOMEPAGE_FILE_XXX}} in any config
+  };
+  # Install the homepage-dashboard configuration files
+  system.activationScripts.installHomepageDashboardConfig = ''
+    mkdir -p configDir
+    ${pkgs.rsync}/bin/rsync -avz --chmod=D2755,F600 ${./config}/ ${configDir}/
+
+    ${pkgs.systemdMinimal}/bin/systemctl restart homepage-dashboard
+  '';
+}