feat(librewolf): expose package as an overridable option

Move librewolf out of the bare package list into its own module declaring
`local.librewolf.package` (default pkgs.librewolf), mirroring texlive. Lets a
consumer swap the wrapped package — extraPolicies/extraPrefs — to share
extensions and an about:config baseline across profiles without editing the
module.

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>

modules/librewolf.nix

@@ -0,0 +1,35 @@
+# LibreWolf browser. The package is an option so a consumer can swap the wrapped
+# package without editing this module: the base is plain pkgs.librewolf, but the
+# wrapper (wrapFirefox) accepts `extraPolicies` and `extraPrefs`, and overriding
+# those is the clean way to manage LibreWolf declaratively.
+#
+# The useful case is sharing state across LibreWolf profiles that otherwise stay
+# separate (each `-P <name>` has its own history/logins/cookies). Enterprise
+# policy `ExtensionSettings` force- or normal-installs the same add-ons into
+# every profile, and `extraPrefs` (autoconfig `defaultPref`/`lockPref`) seeds a
+# shared about:config baseline — both applied per-launch, neither touching
+# per-profile user data. Override, e.g.:
+#
+#   local.librewolf.package = pkgs.librewolf.override {
+#     extraPolicies.ExtensionSettings."uBlock0@raymondhill.net" = {
+#       installation_mode = "normal_installed";
+#       install_url = "https://addons.mozilla.org/firefox/downloads/latest/ublock-origin/latest.xpi";
+#     };
+#     extraPrefs = ''defaultPref("browser.startup.page", 3);'';
+#   };
+{ config, lib, pkgs, ... }:
+
+{
+  options.local.librewolf.package = lib.mkOption {
+    type = lib.types.package;
+    default = pkgs.librewolf;
+    defaultText = lib.literalExpression "pkgs.librewolf";
+    description = ''
+      LibreWolf package. Override with
+      `pkgs.librewolf.override { extraPolicies = …; extraPrefs = …; }`
+      to share extensions/settings across profiles.
+    '';
+  };
+
+  config.home.packages = [ config.local.librewolf.package ];
+}