build(nix/flake): adding tmux-setup script

flake.nix

@@ -7,16 +7,34 @@
   };
   outputs = { self, nixpkgs, flake-utils, c_formatter_42 }:
     flake-utils.lib.eachDefaultSystem (system:
-      let pkgs = nixpkgs.legacyPackages.${system};
+      let
+        pkgs = nixpkgs.legacyPackages.${system};
+        tmux-setup = pkgs.writeShellScriptBin "tmux-setup" ''
+          #!/usr/bin/env sh
+          SESSION="ft_ping"
+          DIR=$(git rev-parse --show-toplevel 2>/dev/null || pwd)
+          if ! tmux has-session -t $SESSION 2>/dev/null; then
+            tmux new-session -d -s $SESSION -c "$DIR" -n dev
+            tmux send-keys -t $SESSION:0 'vim' C-m
+            tmux split-window -h -p 30 -t $SESSION:0 -c "$DIR"
+            tmux send-keys -t $SESSION:0.1 'exec zsh' C-m
+            tmux new-window -t $SESSION:1 -n git -c "$DIR"
+            tmux send-keys -t $SESSION:1 'lazygit' C-m
+          fi
+          tmux select-window -t $SESSION:0
+          tmux select-pane -t $SESSION:0.0
+          tmux attach -t $SESSION
+        '';
       in {
         devShell = pkgs.mkShell {
-          packages = [
+          packages = with pkgs; [
+            tmux-setup
             c_formatter_42.packages.${system}.default
-            pkgs.clang
-            pkgs.clang-tools
-            pkgs.fastmod
-            pkgs.tree
-          ] ++ (if pkgs.stdenv.isLinux then [ pkgs.valgrind ] else [ ]);
+            clang
+            clang-tools
+            fastmod
+            tree
+          ] ++ (if stdenv.isLinux then [ pkgs.valgrind ] else [ ]);
         };
       });
 }