Run Prettier across projects

Problem:
Prettier was not running when I saved Emacs buffers.

Why?
- prettier-js-mode needs needs node; lorri exposes node to direnv; direnv
  exposes node to Emacs; lorri was not working as expected.

Solution:
Now that I'm using nix-buffer, I can properly expose node (and other
dependencies) to my Emacs buffers. Now Prettier is working.

Commentary:
Since prettier hadn't worked for so long, I stopped thinking about it. As such,
I did not include it as a dependency in boilerplate/typescript. I added it
now. I retroactively ran prettier across a few of my frontend projects to unify
the code styling.

I may need to run...
```shell
$ cd ~/briefcase
$ nix-shell
$ npx prettier --list-different "**/*.{js,ts,jsx,tsx,html,css,json}"
```
...to see which files I should have formatted.

website/sandbox/contentful/src/contentful.ts

@@ -8,10 +8,10 @@ let client: ContentfulClientApi;
 
 // Idempotent way to get a reference to the Contentful client.
 export const getClient = (): ContentfulClientApi => {
-  if (typeof client !== 'undefined') {
+  if (typeof client !== "undefined") {
     return client;
   } else {
-    if (typeof space === 'string' && typeof accessToken === 'string') {
+    if (typeof space === "string" && typeof accessToken === "string") {
       let client = createClient({
         space,
         accessToken,
@@ -19,7 +19,9 @@ export const getClient = (): ContentfulClientApi => {
 
       return client;
     } else {
-      throw new Error('Please set CONTENTFUL_SPACE_ID and CONTENTFUL_ACCESS_TOKEN');
+      throw new Error(
+        "Please set CONTENTFUL_SPACE_ID and CONTENTFUL_ACCESS_TOKEN"
+      );
     }
   }
-}
+};