feat: add Telegram bot frontend with message handling

Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>

src/frontends/telegram/handlers.ts

@@ -0,0 +1,17 @@
+import type { NativeAgent } from '../../backends/index.js';
+
+export function isAllowedChat(chatId: number, allowedIds: number[]): boolean {
+  return allowedIds.includes(chatId);
+}
+
+export function createMessageHandler(agent: NativeAgent): (text: string) => Promise<string> {
+  return async (text: string): Promise<string> => {
+    return agent.process(text);
+  };
+}
+
+export function createResetHandler(agent: NativeAgent): () => void {
+  return (): void => {
+    agent.reset();
+  };
+}