fix: add a public Bybit ticker quickstart

examples/Websocket/Public/ws-public-ticker.md

@@ -0,0 +1,18 @@
+Subscribe to the public `tickers.BTCUSDT` topic with `WebsocketClient` and the
+`linear` product category. No API key or secret is needed.
+
+After installing `bybit-api`, save the displayed code as `ws-public.mjs` and run
+`node ws-public.mjs`.
+
+Register the `exception`, `response`, and `update` handlers before calling
+`subscribeV5()`. The example prints the first received price and closes the
+connection. It exits with a nonzero status if the subscription fails or no
+price arrives within 20 seconds.
+
+The output contains `symbol`, `lastPrice` as a decimal string, and the exchange's
+`timestamp` in milliseconds. For a continuous feed, keep the connection open
+and merge ticker deltas into the preceding snapshot. Bybit omits unchanged
+fields from linear ticker deltas, so a message without `lastPrice` does not
+mean the price is zero or unavailable. See the
+[Bybit ticker stream documentation](https://bybit-exchange.github.io/docs/v5/websocket/public/ticker)
+for the message contract.

examples/Websocket/Public/ws-public-ticker.ts

@@ -0,0 +1,46 @@
+import { WebsocketClient } from '../../../src/index';
+
+const wsClient = new WebsocketClient();
+const topic = 'tickers.BTCUSDT';
+let stopped = false;
+
+const timeout = setTimeout(() => {
+  console.error('No BTCUSDT price received within 20 seconds.');
+  stop(1);
+}, 20_000);
+
+function stop(exitCode = 0) {
+  if (stopped) return;
+  stopped = true;
+  clearTimeout(timeout);
+  wsClient.closeAll();
+  process.exitCode = exitCode;
+}
+
+wsClient.on('exception', (error) => {
+  console.error('WebSocket error:', error);
+  stop(1);
+});
+
+wsClient.on('response', (response) => {
+  if (response.op === 'subscribe' && response.success === false) {
+    console.error('Subscription rejected:', response);
+    stop(1);
+  }
+});
+
+wsClient.on('update', (message) => {
+  if (stopped || message.topic !== topic || !message.data?.lastPrice) return;
+
+  console.log({
+    symbol: message.data.symbol,
+    lastPrice: message.data.lastPrice,
+    timestamp: message.ts,
+  });
+  stop();
+});
+
+Promise.all(wsClient.subscribeV5(topic, 'linear')).catch((error) => {
+  console.error('Could not subscribe:', error);
+  stop(1);
+});