fix(weixin): 空token''连接''不再阻塞+409请先扫码登录；Connect空token返回ErrNeedsLogin

面板点''连接''此前触发阻塞式扫码(最长8min)不展示二维码→挂起。修:
- weixin adapter Connect: 空token返回 ErrNeedsLogin(非阻塞), 扫码走独立 login-qr/login-status
- adminChannelOpen: errors.Is(ErrNeedsLogin)→409'该渠道尚未登录:请先扫码登录再连接'(不再500/挂起)
- login_test.go 改用 StartLogin/LoginStatus 驱动(与旧Connect阻塞行为解耦)
build/vet/test 全绿, 已部署.

plugins/channels/weixin_ilink/adapter.go

@@ -75,6 +75,9 @@ var (
 	ErrLoginTimeout = errors.New("weixin_ilink: qr login timed out")
 	// ErrSessionExpired is returned when iLink reports errcode=-14.
 	ErrSessionExpired = errors.New("weixin_ilink: session expired, re-scan required")
+	// ErrNeedsLogin is returned by Connect when no bot_token is configured yet; the
+	// scan-code bind must be driven via the panel login-qr/login-status endpoints.
+	ErrNeedsLogin = errors.New("weixin_ilink: bot not logged in yet, scan the QR")
 	// ErrNoContextToken is returned when a send lacks the peer's context_token.
 	ErrNoContextToken = errors.New("weixin_ilink: no context_token for peer")
 	// ErrProactiveWindow is returned when a proactive push is outside 24h.
@@ -234,9 +237,11 @@ func (a *Adapter) Connect(ctx context.Context) error {
 		return nil
 	}
 	if token == "" {
-		if err := a.login(ctx); err != nil {
-			return fmt.Errorf("weixin_ilink: connect: %w", err)
-		}
+		// No token yet: the scan-code bind must be driven out-of-band (the panel's
+		// login-qr / login-status endpoints, design/08 §4). Never block a "connect"
+		// HTTP call on the waiting QR — surface ErrNeedsLogin so the caller tells the
+		// owner to scan, rather than holding the request for up to the login timeout.
+		return ErrNeedsLogin
 	}
 	a.mu.Lock()
 	a.connected = true