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.

web/shared/ws.js

@@ -1,22 +1,22 @@
 export function connectWs(onMessage) {
-  let ws, retry = 0, closed = false;
-  function open() {
-    const proto = location.protocol === 'https:' ? 'wss' : 'ws';
-    ws = new WebSocket(`${proto}://${location.host}/ws`);
-    ws.addEventListener('open', () => { retry = 0; });
-    ws.addEventListener('message', (ev) => {
-      try { onMessage(JSON.parse(ev.data)); } catch {}
-    });
-    ws.addEventListener('close', () => {
-      if (closed) return;
-      retry = Math.min(retry + 1, 6);
-      setTimeout(open, 500 * 2 ** retry);
-    });
-    ws.addEventListener('error', () => ws.close());
-  }
-  open();
-  return {
-    send(msg) { if (ws?.readyState === WebSocket.OPEN) ws.send(JSON.stringify(msg)); },
-    close()   { closed = true; ws?.close(); }
-  };
+    let ws, retry = 0, closed = false;
+    function open() {
+        const proto = location.protocol === 'https:' ? 'wss' : 'ws';
+        ws = new WebSocket(`${proto}://${location.host}/ws`);
+        ws.addEventListener('open', () => { retry = 0; });
+        ws.addEventListener('message', (ev) => {
+            try { onMessage(JSON.parse(ev.data)); } catch { }
+        });
+        ws.addEventListener('close', () => {
+            if (closed) return;
+            retry = Math.min(retry + 1, 6);
+            setTimeout(open, 500 * 2 ** retry);
+        });
+        ws.addEventListener('error', () => ws.close());
+    }
+    open();
+    return {
+        send(msg) { if (ws?.readyState === WebSocket.OPEN) ws.send(JSON.stringify(msg)); },
+        close() { closed = true; ws?.close(); }
+    };
 }