feat: Add support for Zellij terminal emulator

Implemented logic to detect when running inside Zellij and used its
native actions to rename the current tab and pane using the provided
title arguments. Updated shell shebang to use `#!/usr/bin/env zsh` and
improved variable access for configuration options.

Signed-off-by: Chmouel Boudjnah <chmouel@chmouel.com>

Author: chmouel

zsh-tab-title.plugin.zsh

@@ -1,18 +1,35 @@
-#!/bin/bash
-
-# Set terminal window and tab/icon title
+#!/usr/bin/env zsh
+#bashbash Set terminal window and tab/icon title
 #
 # usage: title short_tab_title long_window_title
 #
 # See: http://www.faqs.org/docs/Linux-mini/Xterm-Title.html#ss3.1
-# Fully supports screen, hyper, iterm, and probably most modern xterm and rxvt
+# Fully supports screen, hyper, iterm, zellij, and probably most modern xterm and rxvt
 # (In screen, only short_tab_title is used)
+
+# Detect Zellij
+_in_zellij() { [[ -n "$ZELLIJ" || -n "$ZELLIJ_SESSION_NAME" ]]; }
+
+# Zellij rename actions
+_zt_rename_tab()  { command zellij action rename-tab  "$1" >/dev/null 2>&1; }
+_zt_rename_pane() { command zellij action rename-pane "$1" >/dev/null 2>&1; }
+
 function title {
   emulate -L zsh
   setopt prompt_subst
-  
+
   [[ "$EMACS" == *term* ]] && return
 
+  # Handle Zellij first - use actual arguments directly
+  if _in_zellij; then
+    # Expand prompt sequences in arguments before passing to zellij
+    local tab_name="$(print -P "$1")"
+    local pane_name="$(print -P "$2")"
+    _zt_rename_tab "$tab_name"
+    _zt_rename_pane "$pane_name"
+    return
+  fi
+
   tabTitle="\$1"
   termTitle="\$2"
 
@@ -43,23 +60,23 @@ function title {
 
 function setTerminalTitleInIdle {
 
-  if [[ "$ZSH_TAB_TITLE_DISABLE_AUTO_TITLE" == true ]]; then
+  if [[ "${ZSH_TAB_TITLE_DISABLE_AUTO_TITLE:-}" == true ]]; then
     return
   fi
 
-  if [[ "$ZSH_TAB_TITLE_ONLY_FOLDER" == true ]]; then
+  if [[ "${ZSH_TAB_TITLE_ONLY_FOLDER:-}" == true ]]; then
     ZSH_THEME_TERM_TAB_TITLE_IDLE=${PWD##*/}
   else
     ZSH_THEME_TERM_TAB_TITLE_IDLE="%20<..<%~%<<" #15 char left truncated PWD
   fi
 
-  if [[ "$ZSH_TAB_TITLE_DEFAULT_DISABLE_PREFIX" == true ]]; then
+  if [[ "${ZSH_TAB_TITLE_DEFAULT_DISABLE_PREFIX:-}" == true ]]; then
   ZSH_TAB_TITLE_PREFIX=""
-  elif [[ -z "$ZSH_TAB_TITLE_PREFIX" ]]; then
+  elif [[ -z "${ZSH_TAB_TITLE_PREFIX:-}" ]]; then
     ZSH_TAB_TITLE_PREFIX="%n@%m:"
   fi
 
-  ZSH_THEME_TERM_TITLE_IDLE="$ZSH_TAB_TITLE_PREFIX %~ $ZSH_TAB_TITLE_SUFFIX"
+  ZSH_THEME_TERM_TITLE_IDLE="${ZSH_TAB_TITLE_PREFIX:-} %~ $ZSH_TAB_TITLE_SUFFIX"
 
   title "$ZSH_THEME_TERM_TAB_TITLE_IDLE" "$ZSH_THEME_TERM_TITLE_IDLE"
 }