chore(boot): default boot.zfs.forceImportRoot = false (silence eval warning)

Nomarchy roots are BTRFS, never ZFS, but the zfs module's `true` default for
forceImportRoot emits a warning on every eval/build ("recommended to set it
to false, the new default from 26.11"). Adopt that default early via
mkDefault — silences the noise, future-proofs for 26.11, and a real ZFS-root
downstream can still force it back on.

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

modules/nixos/default.nix

@@ -69,6 +69,11 @@ in
     console.earlySetup = lib.mkDefault true;
     boot.initrd.systemd.enable = lib.mkDefault true;
 
+    # Nomarchy roots are BTRFS, not ZFS, so adopt the 26.11 default early and
+    # silence the eval warning the old `true` default emits. mkDefault, so a
+    # genuine ZFS-root downstream can still force it back on.
+    boot.zfs.forceImportRoot = lib.mkDefault false;
+
     # ── Wayland session: Hyprland ────────────────────────────────────
     # Installs the binary, registers the session, wires up
     # xdg-desktop-portal-hyprland. Configuration is Home Manager's job.