Add treefmt

Signed-off-by: Nikolaos Karaolidis <nick@karaolidis.com>

hosts/common/shells/bun/default.nix

@@ -1,6 +1 @@
-{ pkgs, ... }:
-pkgs.mkShell {
-  packages = with pkgs; [
-    bun
-  ];
-}
+{ pkgs, ... }: pkgs.mkShell { packages = with pkgs; [ bun ]; }

hosts/common/shells/nodejs/default.nix

@@ -1,6 +1 @@
-{ pkgs, ... }:
-pkgs.mkShell {
-  packages = with pkgs; [
-    nodejs
-  ];
-}
+{ pkgs, ... }: pkgs.mkShell { packages = with pkgs; [ nodejs ]; }

hosts/common/shells/python/default.nix

@@ -1,8 +1,6 @@
 { pkgs, ... }:
 pkgs.mkShell {
-  packages = with pkgs; [
-    (python3.withPackages (python-pkgs: with python-pkgs; [ pip ]))
-  ];
+  packages = with pkgs; [ (python3.withPackages (python-pkgs: with python-pkgs; [ pip ])) ];
 
   shellHook = ''
     if git rev-parse --is-inside-work-tree &> /dev/null; then