Build landing page from Penpot design, with multi-language switcher

Implement the "Desktop dark" Penpot design: nav, hero, about, products
teaser and contact form, with the exported logo and wave artwork and
self-hosted Poppins, Roboto Flex and Chillax fonts.

- Shared page markup in _includes/home.pug; copy in locales/{en,pl}.json
- Footer language switcher and hreflang tags generated from the locales
- Contact form composes a mailto: to the address in _data/site.json
- Stacked layout below 1024px

eleventy.config.js

@@ -2,6 +2,7 @@ import pug from "pug";
 
 export default function (eleventyConfig) {
   eleventyConfig.addPassthroughCopy("src/assets/img");
+  eleventyConfig.addPassthroughCopy("src/assets/fonts");
 
   eleventyConfig.addExtension("pug", {
     compile: (inputContent, inputPath) => {