chore(zsh): cleanup some of the config

.config/zsh/.zshrc

@@ -1,12 +1,18 @@
-if [[ -z "$TMUX" ]]; then
-  tmux new-session -A -s 0
+if [[ -o interactive ]]; then
+    if [[ -z "$TMUX" ]]; then
+        tmux new-session -A -s 0
+    fi
 fi
 
 source $ZDOTDIR/setup-history.zsh
 source $ZDOTDIR/prompts/simple-two-line.zsh
 source $ZDOTDIR/functions.zsh
 source $ZDOTDIR/plugins.zsh
+source $ZDOTDIR/theme.zsh
 
 if [[ $(uname) == "Darwin" ]]; then
     eval "$(/opt/homebrew/bin/brew shellenv)"
 fi
+
+eval "$(atuin init zsh --disable-up-arrow)"
+