feat: add imagemin plugin

packages/plugin-imagemin/index.js

@@ -0,0 +1,14 @@
+// @see https://github.com/Klathmon/imagemin-webpack-plugin#api
+exports.imagemin = {
+	test: /\.(svg|jpe?g|png|gif)$/i,
+}
+
+exports.webpack = function (config, env, opts) {
+	// disable during HMR/development
+	opts.imagemin.disable = !env.production;
+
+	if (!opts.imagemin.disable) {
+		const ImageMin = require('imagemin-webpack-plugin').default;
+		config.plugins.unshift(new ImageMin(opts.imagemin));
+	}
+}

packages/plugin-imagemin/package.json

@@ -0,0 +1,13 @@
+{
+  "version": "0.0.0",
+  "name": "@pwa/plugin-imagemin",
+  "files": [
+    "index.js"
+  ],
+  "engines": {
+    "node": ">=8"
+  },
+  "dependencies": {
+    "imagemin-webpack-plugin": "^2.4.0"
+  }
+}

packages/plugin-imagemin/readme.md

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+# @pwa/plugin-imagemin
+
+> [`PWA`](https://pwa.cafe/) plugin for to compress image assets
+
+## Install
+
+```sh
+$ npm install --save-dev @pwa/plugin-imagemin
+```
+
+## Usage
+
+_None – recognized by and attached to `@pwa/core` automatically!_
+
+> **Note:** Disabled during development (aka, `pwa watch`)
+
+## Config
+
+Configurable via the `imagemin` key on your `pwa.config.js` file.
+
+***Default Config:***
+
+> **Note:** In addition to the below, inherits `imagemin-webpack-plugin` defaults.
+
+```js
+exports.imagemin = {
+  test: /\.(svg|jpe?g|png|gif)$/i
+}
+```
+
+***Available Options:***
+
+See [`imagemin-webpack-plugin`](https://github.com/Klathmon/imagemin-webpack-plugin#api) for documentation.