add zellij installer and update oh-my-posh themes

feat: add zellij installer and update oh-my-posh themes

lk-installers/install-ohmyposh

@@ -1,2 +1 @@
 curl -s https://ohmyposh.dev/install.sh | bash -s
-

lk-installers/install-zellij

@@ -0,0 +1,7 @@
+#!/bin/bash
+
+echo "Installing Zellij via cargo..."
+cargo install zellij || {
+  echo "Cargo failed - trying apt instead"
+  sudo apt update && sudo apt install -y zellij
+}