feat: Telegram Bot API integration

- New client: src/clients/telegram.ts
- Tools: telegram_get_me, telegram_send_message, telegram_send_photo, telegram_get_updates, telegram_get_chat
- REST endpoints: GET /api/telegram/me, POST /api/telegram/message, POST /api/telegram/photo, GET /api/telegram/updates, GET /api/telegram/chat
- Multi-account env var pattern: TELEGRAM_{ACCOUNT}_BOT_TOKEN
- Uses Telegram Bot API (https://api.telegram.org)

Total tools: 24 (email 6, obsidian 5, whatsapp 3, linkedin 4, telegram 5)

.env.example

@@ -54,3 +54,9 @@ LINKEDIN_DEFAULT_ACCESS_TOKEN=your-linkedin-access-token
 LINKEDIN_DEFAULT_CLIENT_ID=your-linkedin-client-id
 LINKEDIN_DEFAULT_CLIENT_SECRET=your-linkedin-client-secret
 # For additional accounts, duplicate with LINKEDIN_{ACCOUNT}_*
+
+# ── Telegram Bot API ─────────────────────────────────────────────────────────
+# Create a bot via @BotFather on Telegram and copy the token
+# For default account:
+TELEGRAM_DEFAULT_BOT_TOKEN=your-telegram-bot-token
+# For additional accounts, duplicate with TELEGRAM_{ACCOUNT}_*