Add type definition for third-party packages that do not have them.

package.json

@@ -24,15 +24,22 @@
   "devDependencies": {
     "@preact/preset-vite": "^2.5.0",
     "@types/babel__core": "^7.20.0",
+    "@types/node": "^18.15.11",
     "@types/webextension-polyfill": "^0.10.0",
     "ava": "^5.2.0",
     "c8": "^7.13.0",
+    "concurrently": "^8.0.1",
+    "cssnano": "^6.0.0",
+    "esbuild": "^0.17.15",
+    "esbuild-copy-static-files": "^0.1.0",
+    "esbuild-sass-plugin": "^2.8.0",
     "postcss": "^8.4.21",
     "sass": "^1.60.0",
     "stylelint": "^15.3.0",
     "stylelint-config-standard-scss": "^7.0.1",
     "trash-cli": "^5.0.0",
     "ts-node": "^10.9.1",
+    "tsx": "^3.12.6",
     "typescript": "^5.0.2",
     "vite": "^4.2.1",
     "vite-plugin-web-extension": "^3.0.2",

source/packages.d.ts

@@ -0,0 +1,15 @@
+// Type definitions for third-party packages.
+
+declare module 'esbuild-copy-static-files' {
+  import {type cpSync} from 'node:fs';
+  import {type Plugin} from 'esbuild';
+
+  type CopySyncParameters = Parameters<typeof cpSync>;
+
+  type Options = {
+    src?: CopySyncParameters[0];
+    dest?: CopySyncParameters[1];
+  } & CopySyncParameters[2];
+
+  export default function (options: Options): Plugin;
+}

source/types.d.ts

@@ -29,4 +29,8 @@ declare global {
 
     type MoveDirection = 'up' | 'down';
   }
+
+  const $browser: 'chromium' | 'firefox';
+  const $dev: boolean;
+  const $test: boolean;
 }