Restructure flake.nix for a simpler config for building different images off the same NixOS config.

nix/configuration/roles/bluetooth/default.nix

@@ -1,7 +1,6 @@
 {
   config,
   lib,
-  pkgs,
   ...
 }:
 
@@ -17,30 +16,23 @@
     };
   };
 
-  config = lib.mkIf config.me.bluetooth.enable (
-    lib.mkMerge [
-      {
-        environment.systemPackages = with pkgs; [
-        ];
-
-        hardware.bluetooth = {
-          enable = true;
-          powerOnBoot = true;
-          settings = {
-            General = {
-              # Enable support for showing battery charge level.
-              Experimental = true;
-            };
-          };
+  config = lib.mkIf config.me.bluetooth.enable {
+    hardware.bluetooth = {
+      enable = true;
+      powerOnBoot = true;
+      settings = {
+        General = {
+          # Enable support for showing battery charge level.
+          Experimental = true;
         };
+      };
+    };
 
-        environment.persistence."/persist" = lib.mkIf (!config.me.buildingIso) {
-          hideMounts = true;
-          directories = [
-            "/var/lib/bluetooth" # Bluetooth pairing information.
-          ];
-        };
-      }
-    ]
-  );
+    environment.persistence."/persist" = lib.mkIf (config.me.mountPersistence) {
+      hideMounts = true;
+      directories = [
+        "/var/lib/bluetooth" # Bluetooth pairing information.
+      ];
+    };
+  };
 }