add a jsconfig file for better autocompletion

This makes editor help, such as autocomplete, much more usefull, while
still allowing me to use absolute paths for imports. The latter is
needed, so that I don't need an extra build step and also don't need to
wory too much about browser imports.

Does this violate the _browser based development_ principle? Yes, a tiny
little bit. However, using an editor is basically required, and making
it that much better seems worthwhile.

Did I waste too much time trying to make this perfect? Also yes. A
strong reminder why that principle is so important.

jsconfig.json

@@ -0,0 +1,10 @@
+{
+  "compilerOptions": {
+    "paths": {
+      "/*": [
+        "./*"
+      ]
+    },
+    "noEmit": true
+  }
+}