Fix OpenRouter hearbeats breaking streaming

src/lib/apis/streaming/index.ts

@@ -31,6 +31,10 @@ async function* openAIStreamToIterator(
 				console.log(line);
 				if (line === 'data: [DONE]') {
 					yield { done: true, value: '' };
+				} if (line.startsWith(':')) {
+					// Events starting with : are comments https://developer.mozilla.org/en-US/docs/Web/API/Server-sent_events/Using_server-sent_events#event_stream_format
+					// OpenRouter sends heartbeats like ": OPENROUTER PROCESSING"
+					continue
 				} else {
 					const data = JSON.parse(line.replace(/^data: /, ''));
 					console.log(data);