include offline copy of docs

This grabs the docs via the @pybricks/ide-docs package and copies them
to the build directory with copy-webpack-plugin.

The service worker automatically picks up these files for precache
since they go through webpack.

package.json

@@ -11,6 +11,7 @@
         "@blueprintjs/core": "^3.38.1",
         "@craco/craco": "^6.0.0",
         "@pybricks/firmware": "4.5.0",
+        "@pybricks/ide-docs": "1.0.0",
         "@pybricks/mpy-cross-v5": "^2.0.0",
         "@shopify/react-i18n": "^5.2.1",
         "@testing-library/dom": "^7.29.2",
@@ -30,6 +31,7 @@
         "@types/zen-push": "^0.1.1",
         "ace-builds": "^1.4.12",
         "babel-plugin-macros": "^3.0.1",
+        "copy-webpack-plugin": "6",
         "file-saver": "^2.0.5",
         "jszip": "^3.5.0",
         "license-webpack-plugin": "^2.3.11",