add tokenizer and chat template

sketch.js

@@ -24,7 +24,11 @@ async function textGenTask(input){
       {"role": "user", "content": input}
     ]
 
-  var out = await pipe(messages, {
+  const prompt = generator.tokenizer.apply_chat_template(messages, {
+    tokenize: false, add_generation_prompt: true,
+  });
+
+  var out = await pipe(prompt, {
     max_new_tokens: 256,
     temperature: 0.7,
     do_sample: true,