Refactor NixOS and Home Manager modules

This makes them more modular and configurable by allowing features to be
enabled per-host.

Squashed commit of the following:

commit e9896d6166125de7aa26ddc63dac3adb196e8c23
Author: Oliver Davies <oliver@oliverdavies.dev>
Date:   Mon Nov 25 23:06:23 2024 +0000

    Use mkMerge

    To ensure features isn't overridden and values aren't lost accidentally

commit c9c8ff5d059f08ade3aee9bb4e25bd51d4817a6d
Author: Oliver Davies <oliver@oliverdavies.dev>
Date:   Mon Nov 25 22:56:38 2024 +0000

    Move NixOS module imports

commit 4a85bbac9dfa8f06825f6b1fee45ef27befa16d3
Author: Oliver Davies <oliver@oliverdavies.dev>
Date:   Mon Nov 25 22:39:54 2024 +0000

    Move Home Manager module imports

commit 6d7a1b0aac68ccc8649fa2d8cd6e8b17ecebb4f0
Author: Oliver Davies <oliver@oliverdavies.dev>
Date:   Mon Nov 25 21:15:54 2024 +0000

    Add host-specific Home Manager configurations

commit b32da2fbf7498c9684d8289be0f02800994e9110
Author: Oliver Davies <oliver@oliverdavies.dev>
Date:   Mon Nov 25 18:00:00 2024 +0000

    Start to parameterise Home Manager modules

commit e80e89b415849cc4c6051a07b70587ac98724e2c
Author: Oliver Davies <oliver@oliverdavies.dev>
Date:   Mon Nov 25 18:00:00 2024 +0000

    Rename wsl commands to home-manager

commit 6d82ed73da3c104fb25117fb843c3f3b5d833180
Author: Oliver Davies <oliver@oliverdavies.dev>
Date:   Mon Nov 25 18:00:00 2024 +0000

    Refactor NixOS Home Manager configuration

commit cc5cbf5ac1a407a456d7258dd65a78ba3128a88f
Author: Oliver Davies <oliver@oliverdavies.dev>
Date:   Mon Nov 25 08:05:00 2024 +0000

    Refactor WSL Home Manager configuration

commit deaf664a0997871b6f2bb0a8f97d638a91cb10bc
Author: Oliver Davies <oliver@oliverdavies.dev>
Date:   Mon Nov 25 08:04:00 2024 +0000

    Refactor lemp11 configuration

nix/home/opdavies/default.nix

@@ -1,13 +1,33 @@
 {
   config,
   desktop,
+  hostname,
   inputs,
-  pkgs,
+  outputs,
   self,
+  system,
   username,
   ...
 }:
 let
+  pkgs = import inputs.nixpkgs {
+    inherit system;
+
+    config = {
+      allowUnfree = true;
+
+      permittedInsecurePackages = [
+        "electron-27.3.11"
+      ];
+    };
+
+    overlays = [
+      outputs.overlays.additions
+      outputs.overlays.modifications
+      outputs.overlays.stable-packages
+    ];
+  };
+
   inherit (pkgs) lib;
 
   desktop-config = import ./desktop.nix {
@@ -18,14 +38,19 @@ let
       username
       ;
   };
+
   shared-config = import "${self}/nix/lib/shared/home-manager.nix" {
     inherit
+      config
+      hostname
       inputs
+      lib
       pkgs
       self
       username
       ;
   };
+
   shared-packages = import "${self}/nix/lib/shared/home-manager-packages.nix" {
     inherit
       desktop

nix/home/opdavies/desktop.nix

@@ -1,18 +1,12 @@
-{
-  config,
-  inputs,
-  pkgs,
-  username,
-}:
+{ ... }:
+
 {
   imports = [
-    ../../modules/home-manager/alacritty.nix
     ../../modules/home-manager/copyq.nix
     ../../modules/home-manager/bluetuith.nix
     ../../modules/home-manager/espanso.nix
     ../../modules/home-manager/gtk.nix
     ../../modules/home-manager/flameshot.nix
     ../../modules/home-manager/gtk.nix
-    ../../modules/home-manager/mpv.nix
   ];
 }

nix/home/opdavies/hosts/PW05CH3L.nix

@@ -0,0 +1,7 @@
+{
+  features = {
+    desktop = {
+      alacritty.enable = false;
+    };
+  };
+}

nix/home/opdavies/hosts/lemp11.nix

@@ -0,0 +1,9 @@
+{ ... }:
+
+{
+  features = {
+    desktop = {
+      mpv.enable = true;
+    };
+  };
+}