persistence: Rename module

`impermanence` -> `persistence`

modules/system/persistence.nix

@@ -0,0 +1,44 @@
+{
+  config,
+  inputs,
+  lib,
+  ...
+}:
+let
+  cfg = config.custom.persistence;
+in
+{
+  imports = [ inputs.impermanence.nixosModules.impermanence ];
+
+  options.custom.persistence = {
+    enable = lib.mkEnableOption "";
+    directories = lib.mkOption {
+      type = lib.types.listOf lib.types.path;
+      default = [ ];
+    };
+  };
+
+  config = lib.mkIf cfg.enable {
+    fileSystems."/persist".neededForBoot = true;
+
+    security.sudo.extraConfig = "Defaults lecture=never";
+
+    environment.persistence."/persist" = {
+      hideMounts = true;
+
+      # See https://nixos.org/manual/nixos/stable/#ch-system-state
+      directories = [
+        "/var/lib/nixos"
+        "/var/lib/systemd"
+        "/var/log"
+      ]
+      ++ config.custom.persistence.directories;
+
+      files = [
+        "/etc/machine-id"
+        "/etc/ssh/ssh_host_ed25519_key"
+        "/etc/ssh/ssh_host_ed25519_key.pub"
+      ];
+    };
+  };
+}