refactor(hardware): reorganize module structure

modules/nixos/hardware/audio.nix

@@ -0,0 +1,13 @@
+{
+  flake.modules.nixos.hardware = {
+    security.rtkit.enable = true;
+
+    services.pipewire = {
+      enable = true;
+      alsa.enable = true;
+      alsa.support32Bit = true;
+      pulse.enable = true;
+      wireplumber.enable = true;
+    };
+  };
+}

modules/nixos/hardware/graphics.nix

@@ -0,0 +1,13 @@
+{
+  flake.modules.nixos.hardware = {
+    hardware = {
+      graphics = {
+        enable = true;
+        enable32Bit = true;
+      };
+
+      enableAllFirmware = true;
+      usb-modeswitch.enable = true;
+    };
+  };
+}