nix: replace treefmt with alejandra

flake.lock

@@ -211,8 +211,7 @@
         "flake-parts": "flake-parts",
         "mmsg": "mmsg",
         "nixpkgs": "nixpkgs",
-        "nixpkgs-wayland": "nixpkgs-wayland",
-        "treefmt-nix": "treefmt-nix"
+        "nixpkgs-wayland": "nixpkgs-wayland"
       }
     },
     "systems": {
@@ -229,26 +228,6 @@
         "repo": "default",
         "type": "github"
       }
-    },
-    "treefmt-nix": {
-      "inputs": {
-        "nixpkgs": [
-          "nixpkgs"
-        ]
-      },
-      "locked": {
-        "lastModified": 1749194973,
-        "narHash": "sha256-eEy8cuS0mZ2j/r/FE0/LYBSBcIs/MKOIVakwHVuqTfk=",
-        "owner": "numtide",
-        "repo": "treefmt-nix",
-        "rev": "a05be418a1af1198ca0f63facb13c985db4cb3c5",
-        "type": "github"
-      },
-      "original": {
-        "owner": "numtide",
-        "repo": "treefmt-nix",
-        "type": "github"
-      }
     }
   },
   "root": "root",