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/switch.go

@@ -23,13 +23,14 @@ type Switch interface {
 	ToggleChannel(ctx context.Context, ch int) error
 	IsChannelOn(ctx context.Context, ch int) (bool, error)
 
-	OnStateChanged(handler func(on bool)) (string, error)
+	OnStateChanged(handler func(ch int, on bool)) (string, error)
 }
 
 // switchDevice is the concrete Switch implementation.
 type switchDevice struct {
 	BaseDevice
-	channels []siidPiid // "on" property per channel (index 0 = channel 1)
+	channels   []siidPiid // "on" property per channel (index 0 = channel 1)
+	stateCache []bool      // MQTT 推送维护的本地缓存，索引 0 = 通道 1
 }
 
 type siidPiid struct {
@@ -63,6 +64,7 @@ func NewSwitch(client *xiaomi.Client, info *xiaomi.DeviceInfo) (Switch, error) {
 		return nil, xiaomi.ErrNotSupported
 	}
 	d.channels = channels
+	d.stateCache = make([]bool, len(channels))
 
 	return d, nil
 }
@@ -129,14 +131,25 @@ func (d *switchDevice) IsChannelOn(ctx context.Context, ch int) (bool, error) {
 	return false, nil
 }
 
-func (d *switchDevice) OnStateChanged(handler func(on bool)) (string, error) {
-	p, ok := d.channel(1)
-	if !ok {
+func (d *switchDevice) OnStateChanged(handler func(ch int, on bool)) (string, error) {
+	if len(d.channels) == 0 {
 		return "", xiaomi.ErrNotSupported
 	}
-	return d.SubProp(p.siid, p.piid, func(did string, prop *xiaomi.PropertyValue) {
-		if b, ok := prop.Value.(bool); ok {
-			handler(b)
+	// 构建 siid/piid → channel index 的快速查找表
+	type chField struct{ siid, piid int }
+	lookup := make(map[chField]int) // key → channel index (0-based)
+	for i, c := range d.channels {
+		lookup[chField{c.siid, c.piid}] = i
+	}
+	return d.SubProp(0, 0, func(did string, prop *xiaomi.PropertyValue) {
+		for k, idx := range lookup {
+			if k.siid == prop.SIID && k.piid == prop.PIID {
+				if b, ok := prop.Value.(bool); ok {
+					d.stateCache[idx] = b
+					handler(idx+1, b) // ch = idx+1
+				}
+				return
+			}
 		}
 	})
 }