refactor: 重构 token 管理，新增 NATS adapter 和多示例

按照 TOKEN_REFACTOR.md / FIX_CONFIG.md 方案重构核心层：
- miot: Init() 优先读 storage token，新增 RefreshAuthInfo() 和刷新回调
- xiaomi: Config 改用 AuthInfo 结构体（含 UUID/UID/DataDir/OnTokenRefreshed）
- xiaomi: NewClient(ctx, Config) 新签名，新增 RefreshToken()，后台自动刷新
- xiaomi/devices: 设备控制接口重构
- 新增示例 12_ac_subscribe，其余示例适配新 Config

xiaomi/devices/cover.go

@@ -12,14 +12,18 @@ type Cover interface {
 	Close(ctx context.Context) error
 	Stop(ctx context.Context) error
 
-	SetPosition(ctx context.Context, pct int) error // 0=关, 100=全开
+	SetPosition(ctx context.Context, pct int) error
 	GetPosition(ctx context.Context) (int, error)
+
+	OnStateChanged(handler func(position int)) (string, error)
 }
 
 type coverDevice struct {
 	BaseDevice
-	propMotor    siidPiid // "motor-control" — open/close/stop
-	propPosition siidPiid // "current-position"
+	propMotor    siidPiid
+	propPosition siidPiid
+
+	stateCache int
 }
 
 const (
@@ -28,65 +32,52 @@ const (
 	coverMotorStop  = 2
 )
 
-// NewCover creates a Cover control for the given device.
 func NewCover(client *xiaomi.Client, info *xiaomi.DeviceInfo) (Cover, error) {
-	d := &coverDevice{
-		BaseDevice: NewBaseDevice(client, info),
-	}
-
+	d := &coverDevice{BaseDevice: NewBaseDevice(client, info)}
 	resolver := d.getSpecResolver()
 	if resolver == nil {
 		return nil, xiaomi.ErrNoSPEC
 	}
-
 	siid, piid, ok := resolver.find("motor-control")
 	if !ok {
 		return nil, xiaomi.ErrNotSupported
 	}
 	d.propMotor = siidPiid{siid, piid, true}
-
 	if s, p, ok := resolver.find("current-position"); ok {
 		d.propPosition = siidPiid{s, p, true}
 	}
-
 	return d, nil
 }
 
 func (d *coverDevice) Open(ctx context.Context) error {
-	if !d.propMotor.valid {
-		return xiaomi.ErrNotSupported
-	}
+	if !d.propMotor.valid { return xiaomi.ErrNotSupported }
 	return d.SetProp(ctx, d.propMotor.siid, d.propMotor.piid, coverMotorOpen)
 }
-
 func (d *coverDevice) Close(ctx context.Context) error {
-	if !d.propMotor.valid {
-		return xiaomi.ErrNotSupported
-	}
+	if !d.propMotor.valid { return xiaomi.ErrNotSupported }
 	return d.SetProp(ctx, d.propMotor.siid, d.propMotor.piid, coverMotorClose)
 }
-
 func (d *coverDevice) Stop(ctx context.Context) error {
-	if !d.propMotor.valid {
-		return xiaomi.ErrNotSupported
-	}
+	if !d.propMotor.valid { return xiaomi.ErrNotSupported }
 	return d.SetProp(ctx, d.propMotor.siid, d.propMotor.piid, coverMotorStop)
 }
-
 func (d *coverDevice) SetPosition(ctx context.Context, pct int) error {
-	if !d.propPosition.valid {
-		return xiaomi.ErrNotSupported
-	}
+	if !d.propPosition.valid { return xiaomi.ErrNotSupported }
 	return d.SetProp(ctx, d.propPosition.siid, d.propPosition.piid, pct)
 }
-
 func (d *coverDevice) GetPosition(ctx context.Context) (int, error) {
-	if !d.propPosition.valid {
-		return 0, xiaomi.ErrNotSupported
-	}
+	if !d.propPosition.valid { return 0, xiaomi.ErrNotSupported }
 	prop, err := d.GetProp(ctx, d.propPosition.siid, d.propPosition.piid)
-	if err != nil {
-		return 0, err
-	}
+	if err != nil { return 0, err }
 	return toInt(prop.Value), nil
 }
+
+func (d *coverDevice) OnStateChanged(handler func(position int)) (string, error) {
+	if !d.propPosition.valid { return "", xiaomi.ErrNotSupported }
+	return d.SubProp(0, 0, func(did string, prop *xiaomi.PropertyValue) {
+		if prop.SIID == d.propPosition.siid && prop.PIID == d.propPosition.piid {
+			d.stateCache = toInt(prop.Value)
+			handler(d.stateCache)
+		}
+	})
+}