Add .tmux script

[ci skip]

.tmux

@@ -0,0 +1,27 @@
+#!/usr/bin/env bash
+
+set -o errexit
+set -o nounset
+
+session_name="${1:-'build-configs'}"
+session_path="${2:-$(pwd)}"
+
+if tmux has-session -t="${session_name}" 2> /dev/null; then
+  tmux attach -t "${session_name}"
+  exit
+fi
+
+tmux new-session -d -s "${session_name}" -n vim -c "${session_path}"
+
+# 1. Main window: Vim.
+tmux send-keys -t "${session_name}:vim" "nvim +GoToFile" Enter
+
+# 2. General shell use.
+tmux new-window -t "${session_name}" -c "${session_path}"
+
+if [[ -n "${TMUX:-}" ]]; then
+  tmux switch-client -t "${session_name}"
+  tmux select-window -t "${session_name}:vim.left"
+else
+  tmux attach -t "${session_name}:vim.left"
+fi