Add new theme: axira

Add initial version of the Axira Zsh theme.
Features:
- VPN IP detection with fallback to eth0
- Smart icon: 🔒 for VPN, 🌐 when not connected
- Python venv and Git branch shown
- Clean multi-line style with Nerd Font symbols

themes/axira.zsh-theme

@@ -0,0 +1,47 @@
+# ~/.oh-my-zsh/custom/themes/axira.zsh-theme
+
+autoload -U colors && colors
+
+local BLUE="%F{33}"
+local GREEN="%F{76}"
+local RED="%F{196}"
+local YELLOW="%F{226}"
+local MAGENTA="%F{201}"
+local CYAN="%F{51}"
+local RESET="%f%k"
+
+local PROMPT_CORNER="┌─"
+local PROMPT_BOTTOM="└─"
+local PROMPT_ARROW="➜"
+
+get_ip() {
+  local ip=$(ip -4 addr show tun0 2>/dev/null | grep -oP '(?<=inet\s)\d+(\.\d+){3}' | head -1)
+  if [[ -z "$ip" ]]; then
+    ip=$(ip -4 addr show eth0 2>/dev/null | grep -oP '(?<=inet\s)\d+(\.\d+){3}' | head -1)
+  fi
+  [[ -z "$ip" ]] && ip="NoNet"
+  echo "$ip"
+}
+
+get_ip_icon() {
+  ip link show tun0 2>/dev/null | grep -q "state UP" && echo "🔒" || echo "🌐"
+}
+
+git_branch() {
+  local branch=$(git rev-parse --abbrev-ref HEAD 2>/dev/null)
+  [[ -n "$branch" ]] && echo "%{$YELLOW%} $branch%{$RESET%}"
+}
+
+python_venv() {
+  [[ -n "$VIRTUAL_ENV" ]] && echo "%{$MAGENTA%}[🐍 $(basename $VIRTUAL_ENV)]%{$RESET%}"
+}
+
+exit_status() {
+  [[ $? -eq 0 ]] && echo "%{$GREEN%}✔%{$RESET%}" || echo "%{$RED%}✗%{$RESET%}"
+}
+
+PROMPT='
+%{$CYAN%}${PROMPT_CORNER}[%{$BLUE%}%~%{$CYAN%}] [%{$CYAN%}$(get_ip_icon) %{$GREEN%}$(get_ip)%{$CYAN%}] $(python_venv) $(git_branch)
+%{$CYAN%}${PROMPT_BOTTOM}${PROMPT_ARROW} %{$RESET%}'
+
+RPROMPT='$(exit_status)'