Implement *_reply for the web

Also, start extracting shared components

website/src/components/Messages.tsx

@@ -0,0 +1,18 @@
+export interface Message {
+  text: string;
+  is_assistant: boolean;
+}
+
+const getColor = (isAssistant: boolean) => (isAssistant ? "bg-slate-800" : "bg-sky-900");
+
+export const Messages = ({ messages }: { messages: Message[] }) => {
+  const items = messages.map(({ text, is_assistant }: Message, i: number) => {
+    return (
+      <div key={i + text} className={`${getColor(is_assistant)} p-4 my-1 rounded-xl text-white whitespace-pre-wrap`}>
+        {text}
+      </div>
+    );
+  });
+  // Maybe also show a legend of the colors?
+  return <>{items}</>;
+};