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.

scratch/deepmind/part_two/package-lock.json

@@ -28,6 +28,12 @@
       "integrity": "sha512-c3sIjNUow0+8swNwVpqoH4YCShKNFkMaw6oH1mNS2haDZQqkeZFlHS3dhoeEbKKmJB4vXpJucU6oH75aDYeE9g==",
       "dev": true
     },
+    "prettier": {
+      "version": "2.0.2",
+      "resolved": "https://registry.npmjs.org/prettier/-/prettier-2.0.2.tgz",
+      "integrity": "sha512-5xJQIPT8BraI7ZnaDwSbu5zLrB6vvi8hVV58yHQ+QK64qrY40dULy0HSRlQ2/2IdzeBpjhDkqdcFBnFeDEMVdg==",
+      "dev": true
+    },
     "source-map": {
       "version": "0.6.1",
       "resolved": "https://registry.npmjs.org/source-map/-/source-map-0.6.1.tgz",

scratch/deepmind/part_two/package.json

@@ -9,6 +9,7 @@
   "author": "William Carroll",
   "license": "MIT",
   "devDependencies": {
+    "prettier": "^2.0.2",
     "ts-node": "^8.6.2",
     "typescript": "^3.7.5"
   }

scratch/deepmind/part_two/top-scores.ts

@@ -8,7 +8,7 @@ function sortScores(xs: Array<number>, highest: number): Array<number> {
   }
 
   for (let i = 0; i < xs.length; i += 1) {
-    counts[xs[i]] += 1
+    counts[xs[i]] += 1;
   }
 
   for (let i = highest; i >= 0; i -= 1) {
@@ -22,29 +22,28 @@ function sortScores(xs: Array<number>, highest: number): Array<number> {
   return result;
 }
 
-
 // Tests
-let desc = 'no scores';
+let desc = "no scores";
 let actual = sortScores([], 100);
 let expected = [];
 assertEqual(JSON.stringify(actual), JSON.stringify(expected), desc);
 
-desc = 'one score';
+desc = "one score";
 actual = sortScores([55], 100);
 expected = [55];
 assertEqual(JSON.stringify(actual), JSON.stringify(expected), desc);
 
-desc = 'two scores';
+desc = "two scores";
 actual = sortScores([30, 60], 100);
 expected = [60, 30];
 assertEqual(JSON.stringify(actual), JSON.stringify(expected), desc);
 
-desc = 'many scores';
+desc = "many scores";
 actual = sortScores([37, 89, 41, 65, 91, 53], 100);
 expected = [91, 89, 65, 53, 41, 37];
 assertEqual(JSON.stringify(actual), JSON.stringify(expected), desc);
 
-desc = 'repeated scores';
+desc = "repeated scores";
 actual = sortScores([20, 10, 30, 30, 10, 20], 100);
 expected = [30, 30, 20, 20, 10, 10];
 assertEqual(JSON.stringify(actual), JSON.stringify(expected), desc);