fix: centralize and nixifiy in 'zk' module

home/modules/zk/scripts/zk.sh

@@ -0,0 +1,29 @@
+current_zettel_path="$ZK_PATH/$(cat "$ZK_PATH/current-zettel.txt")"
+
+if [ -n "${TMUX:-}" ]; then
+  cd "$ZK_PATH" && $EDITOR "$current_zettel_path"
+else
+  echo 'Not in tmux'
+  echo 'Choose an option:'
+  echo '1. Open in tmux'
+  echo '2. Open in current terminal'
+  read -r -p 'Enter your choice: ' choice
+  case $choice in
+    1)
+      if tmux has-session -t zk 2>/dev/null; then
+        tmux attach -t zk
+      else
+        tmux new-session -s zk -n zk -d
+        tmux send-keys -t zk:zk "cd $ZK_PATH && $EDITOR $current_zettel_path" Enter
+        tmux attach -t zk
+      fi
+      ;;
+    2)
+      cd "$ZK_PATH" && $EDITOR "$current_zettel_path"
+      ;;
+    *)
+      echo 'Not opening Zettelkasten'
+      exit 1
+      ;;
+  esac
+fi