Add API documentation and underground station importer

- Introduced a new HTML documentation page for the oradio API, including a JavaScript file to handle dynamic content and API requests.
- Added a CSS file for styling the documentation page.
- Implemented an underground station importer script that fetches data from Radio-Browser and writes it to a JSON file.
- Created a stats module to compute and manage vote and play statistics for radio stations.
- Added a polyfill for modulepreload to ensure compatibility with older browsers.

server/public/assets/modulepreload-polyfill-B5Qt9EMX.js

@@ -0,0 +1 @@
+(function(){const t=document.createElement("link").relList;if(t&&t.supports&&t.supports("modulepreload"))return;for(const e of document.querySelectorAll('link[rel="modulepreload"]'))i(e);new MutationObserver(e=>{for(const r of e)if(r.type==="childList")for(const o of r.addedNodes)o.tagName==="LINK"&&o.rel==="modulepreload"&&i(o)}).observe(document,{childList:!0,subtree:!0});function s(e){const r={};return e.integrity&&(r.integrity=e.integrity),e.referrerPolicy&&(r.referrerPolicy=e.referrerPolicy),e.crossOrigin==="use-credentials"?r.credentials="include":e.crossOrigin==="anonymous"?r.credentials="omit":r.credentials="same-origin",r}function i(e){if(e.ep)return;e.ep=!0;const r=s(e);fetch(e.href,r)}})();