docs(channels): add Channels feature documentation

- Add overview page explaining channels architecture and configuration
- Add Telegram channel setup guide with bot creation steps
- Add navigation entries for channels section

This documents the new Channels feature that allows users to interact
with Qwen Code agents from messaging platforms like Telegram.

Co-authored-by: Qwen-Coder <qwen-coder@alibabacloud.com>

docs/users/features/channels/telegram.md

@@ -0,0 +1,85 @@
+# Telegram
+
+This guide covers setting up a Qwen Code channel on Telegram.
+
+## Prerequisites
+
+- A Telegram account
+- A Telegram bot token (see below)
+
+## Creating a Bot
+
+1. Open Telegram and search for [@BotFather](https://t.me/BotFather)
+2. Send `/newbot` and follow the prompts to choose a name and username
+3. BotFather will give you a bot token — save it securely
+
+## Finding Your User ID
+
+To use `senderPolicy: "allowlist"`, you need your Telegram user ID (a numeric ID, not your username).
+
+The easiest way to find it:
+
+1. Search for [@userinfobot](https://t.me/userinfobot) on Telegram
+2. Send it any message — it will reply with your user ID
+
+## Configuration
+
+Add the channel to `~/.qwen/settings.json`:
+
+```json
+{
+  "channels": {
+    "my-telegram": {
+      "type": "telegram",
+      "token": "$TELEGRAM_BOT_TOKEN",
+      "senderPolicy": "allowlist",
+      "allowedUsers": ["YOUR_USER_ID"],
+      "sessionScope": "user",
+      "cwd": "/path/to/your/project",
+      "instructions": "You are a concise coding assistant responding via Telegram. Keep responses short."
+    }
+  }
+}
+```
+
+Set the bot token as an environment variable:
+
+```bash
+export TELEGRAM_BOT_TOKEN=<your-token-from-botfather>
+```
+
+Or add it to a `.env` file that gets sourced before running.
+
+## Running
+
+```bash
+qwen channel start my-telegram
+```
+
+Then open your bot in Telegram and send a message. You should see "Working..." appear immediately, followed by the agent's response.
+
+## Tips
+
+- **Keep instructions concise-focused** — Telegram has a 4096-character message limit. Adding instructions like "keep responses short" helps the agent stay within bounds.
+- **Use `sessionScope: "user"`** — This gives each user their own conversation. Use `/reset` to start fresh.
+- **Restrict access** — Use `senderPolicy: "allowlist"` with your user ID to prevent unauthorized access. The bot silently ignores messages from users not on the list.
+
+## Message Formatting
+
+The agent's markdown responses are automatically converted to Telegram-compatible HTML. Code blocks, bold, italic, links, and lists are all supported.
+
+## Troubleshooting
+
+### Bot doesn't respond
+
+- Check that the bot token is correct and the environment variable is set
+- Verify your user ID is in `allowedUsers` if using `senderPolicy: "allowlist"`
+- Check the terminal output for errors
+
+### "Sorry, something went wrong processing your message"
+
+This usually means the agent encountered an error. Check the terminal output for details.
+
+### Bot takes a long time to respond
+
+The agent may be running multiple tool calls (reading files, searching, etc.). The "Working..." indicator shows while the agent is processing. Complex tasks can take a minute or more.