feat(channels): add Telegram channel integration with ACP bridge

Implements the channels infrastructure for connecting external messaging
platforms to Qwen Code via ACP. Phase 1 supports plain text round-trip:
Telegram user sends message -> AcpBridge -> qwen-code --acp -> response
back to Telegram.

New packages:
- @qwen-code/channel-base: AcpBridge, SessionRouter, SenderGate, ChannelBase
- @qwen-code/channel-telegram: TelegramAdapter using telegraf

CLI: `qwen channel start <name>` reads from settings.json channels config,
spawns ACP agent, connects to Telegram via polling.

packages/cli/src/config/config.ts

@@ -51,6 +51,7 @@ import { getCliVersion } from '../utils/version.js';
 import { loadSandboxConfig } from './sandboxConfig.js';
 import { appEvents } from '../utils/events.js';
 import { mcpCommand } from '../commands/mcp.js';
+import { channelCommand } from '../commands/channel.js';
 
 // UUID v4 regex pattern for validation
 const SESSION_ID_REGEX =
@@ -590,7 +591,9 @@ export async function parseArguments(): Promise<CliArgs> {
     // Register Auth subcommands
     .command(authCommand)
     // Register Hooks subcommands
-    .command(hooksCommand);
+    .command(hooksCommand)
+    // Register Channel subcommands
+    .command(channelCommand);
 
   yargsInstance
     .version(await getCliVersion()) // This will enable the --version flag based on package.json
@@ -611,7 +614,8 @@ export async function parseArguments(): Promise<CliArgs> {
     result._.length > 0 &&
     (result._[0] === 'mcp' ||
       result._[0] === 'extensions' ||
-      result._[0] === 'hooks')
+      result._[0] === 'hooks' ||
+      result._[0] === 'channel')
   ) {
     // MCP/Extensions/Hooks commands handle their own execution and process exit
     process.exit(0);