Finish modularising config

There are still some things I want to change, but at least there aren't two systems now.

modules/pass.nix

@@ -0,0 +1,25 @@
+{ config, lib, ... }:
+
+{
+  options.chvp.pass.enable = lib.mkOption {
+    default = false;
+    example = true;
+  };
+
+  config = lib.mkIf config.chvp.pass.enable {
+    nixpkgs.overlays = [
+      (self: super: {
+        firefox = super.firefox.override { extraNativeMessagingHosts = [ self.passff-host ]; };
+        pass = (super.pass.override { pass = super.pass-wayland; }).withExtensions (ext: [ ext.pass-otp ]);
+      })
+    ];
+
+    home-manager.users.charlotte = { ... }: {
+      programs.password-store = {
+        enable = true;
+        settings = { PASSWORD_STORE_DIR = "/home/charlotte/repos/passwords"; };
+      };
+      services.password-store-sync.enable = true;
+    };
+  };
+}