feat: add auth gate and Chinese command parsing

Co-authored-by: Cursor <cursoragent@cursor.com>

src/commands.ts

@@ -0,0 +1,39 @@
+export const MSG = {
+  DENIED: '无权限。',
+  WELCOME:
+    '你好，我是 DeepSeek Harness 渠道机器人。直接发消息开始对话，或发送 /help 查看命令。',
+  HELP: [
+    '/start — 开始 / 欢迎',
+    '/new 或 /clear — 新开会话',
+    '/help — 显示帮助',
+    '',
+    '仅白名单用户可对话；会话在内存中，重启 Harness 后需重新发消息建立。',
+  ].join('\n'),
+  NEW_SESSION: '已开启新会话。',
+  unknown(command: string): string {
+    return `未知命令 ${command}。发送 /help 查看可用命令。`
+  },
+} as const
+
+export type ParsedCommand =
+  | { type: 'start'; text: string }
+  | { type: 'help'; text: string }
+  | { type: 'new'; text: string }
+  | { type: 'unknown'; command: string; text: string }
+  | { type: 'plain'; text: string }
+
+export function parseCommand(text: string): ParsedCommand {
+  if (!text.startsWith('/')) return { type: 'plain', text }
+  const command = text.split(/\s+/)[0] ?? text
+  switch (command) {
+    case '/start':
+      return { type: 'start', text }
+    case '/help':
+      return { type: 'help', text }
+    case '/new':
+    case '/clear':
+      return { type: 'new', text }
+    default:
+      return { type: 'unknown', command, text }
+  }
+}