feat: add WeChat QR code login and AGP WebSocket channel plugin

- Auth module: WeChat OAuth2 scan-to-login flow with terminal QR code
- Token persistence to ~/.openclaw/wechat-access-auth.json (chmod 600)
- Token resolution: config > saved state > interactive login
- Invite code verification (configurable bypass)
- Production/test environment support
- AGP WebSocket client with heartbeat, reconnect, wake detection
- Message handler: Agent dispatch with streaming text and tool calls
- Random device GUID generation (persisted, no real machine ID)

auth/index.ts

@@ -0,0 +1,19 @@
+/**
+ * @file auth/index.ts
+ * @description 认证模块导出
+ */
+
+export type {
+  QClawEnvironment,
+  LoginCredentials,
+  PersistedAuthState,
+  QClawApiResponse,
+} from "./types.js";
+export { TokenExpiredError } from "./types.js";
+
+export { getEnvironment } from "./environments.js";
+export { getDeviceGuid } from "./device-guid.js";
+export { QClawAPI } from "./qclaw-api.js";
+export { loadState, saveState, clearState } from "./state-store.js";
+export { performLogin } from "./wechat-login.js";
+export type { PerformLoginOptions } from "./wechat-login.js";