fix: Remove incorrect ./parts/fleet-data.nix import from flake.nix and use correct flake-parts structure

fleet/fleet-option.nix

@@ -3,8 +3,7 @@
 # ============================================================================
 # This module only defines the athenix.fleet option without any dependencies.
 # Used by fleet/default.nix to evaluate inventory data without circular dependencies.
-{ inputs, ... }:
-{ lib, ... }:
+{ inputs, lib, ... }:
 let
   fleetDefinition = lib.mkOption {
     description = "Hardware types definitions for the fleet.";
@@ -70,6 +69,5 @@ in
     };
   };
 
-  config.athenix.fleet = lib.mkDefault (import ../inventory.nix);
   config.athenix.hwTypes = lib.mkDefault (import ../hw { inherit inputs; });
 }