feat(zfs): declare ZFS module

hosts/andromache/default.nix

@@ -91,6 +91,7 @@ in
     enable = true;
     interfaces.eno1 = { inherit (wolInterfaces.eno1) macAddress; };
   };
+  zfs.enable = true;
 
   disko.devices = {
     disk.data = {

hosts/astyanax/default.nix

@@ -67,6 +67,7 @@ in
     };
   };
   taskwarrior.enable = true;
+  zfs.enable = true;
 
   secrets.nixSigningKey.enable = true;
   restic-backup.enable = true;

modules/common/default.nix

@@ -12,7 +12,6 @@
 
   config = {
     system.stateVersion = lib.mkDefault "25.05";
-    boot.zfs.forceImportRoot = lib.mkDefault false;
 
     environment.defaultPackages = lib.mkForce [ ];
     environment.pathsToLink = [

modules/zfs/default.nix

@@ -0,0 +1,15 @@
+{ lib, config, ... }:
+
+{
+  options.zfs.enable = lib.mkOption {
+    default = false;
+    type = lib.types.bool;
+  };
+
+  config = lib.mkIf config.zfs.enable {
+    boot = {
+      kernelParams = [ "zfs.zfs_arc_max=12884901888" ];
+      zfs.forceImportRoot = lib.mkDefault false;
+    };
+  };
+}