fix: centralize and nixifiy in 'zk' module

home/modules/zk/scripts/setup-zk.sh

@@ -0,0 +1,13 @@
+if [ ! -d "$ZK_PATH" ]; then
+  echo "[zk] Setting up zettelkasten"
+  gh repo clone zk "$ZK_PATH"
+else
+  echo "[zk] Zettelkasten already set up."
+fi
+
+read -p "Would you like open your zettelkasten? [y/N] " -n 1 -r
+echo
+
+if [[ $REPLY =~ ^[Yy]$ ]]; then
+  $EDITOR "$ZK_PATH"
+fi