Use temp dir for dev server build dir.

.gitignore

@@ -1,3 +1,4 @@
 /.parcel-cache
+/.temp
 /dist
 /node_modules

script/dev.js

@@ -2,4 +2,5 @@ import { barelyServe } from "barely-a-dev-server";
 
 barelyServe({
   entryRoot: "src/dev",
+  outDir: "./.temp/dev",
 });