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/light.go

@@ -29,15 +29,15 @@ type Light interface {
 	SetColor(ctx context.Context, r, g, b int) error
 	GetColor(ctx context.Context) (r, g, b int, err error)
 
-	OnStateChanged(handler func(state LightState)) (string, error)
+	OnStateChanged(handler func(state LightState, changed string)) (string, error)
 }
 
-// LightState 灯光完整状态
+// LightState 灯光完整状态（字段名对齐 SPEC type）
 type LightState struct {
-	Power      bool   `json:"power"`
-	Brightness int    `json:"brightness"`
-	ColorTemp  int    `json:"color_temp"`
-	ColorRGB   [3]int `json:"color_rgb"`
+	On               bool   `json:"on"`                // SPEC: "on"
+	Brightness       int    `json:"brightness"`        // SPEC: "brightness"
+	ColorTemperature int    `json:"colorTemperature"`  // SPEC: "color-temperature"
+	ColorRGB         [3]int `json:"colorRgb"`          // SPEC: "color"
 }
 
 type lightDevice struct {
@@ -46,6 +46,8 @@ type lightDevice struct {
 	propBrightness siidPiid // "brightness"
 	propColorTemp  siidPiid // "color-temperature"
 	propColor      siidPiid // "color"
+
+	stateCache LightState // MQTT 推送维护的本地缓存
 }
 
 // NewLight creates a Light control for the given device.
@@ -179,16 +181,45 @@ func (d *lightDevice) GetColor(ctx context.Context) (r, g, b int, err error) {
 	return r, g, b, nil
 }
 
-func (d *lightDevice) OnStateChanged(handler func(state LightState)) (string, error) {
-	if !d.propOn.valid {
+func (d *lightDevice) OnStateChanged(handler func(state LightState, changed string)) (string, error) {
+	type field struct {
+		siid, piid int
+		name       string
+		fill       func(*LightState, interface{})
+	}
+	var fields []field
+	if d.propOn.valid {
+		fields = append(fields, field{d.propOn.siid, d.propOn.piid, "on",
+			func(s *LightState, v interface{}) { s.On, _ = v.(bool) }})
+	}
+	if d.propBrightness.valid {
+		fields = append(fields, field{d.propBrightness.siid, d.propBrightness.piid, "brightness",
+			func(s *LightState, v interface{}) { s.Brightness = toInt(v) }})
+	}
+	if d.propColorTemp.valid {
+		fields = append(fields, field{d.propColorTemp.siid, d.propColorTemp.piid, "color-temperature",
+			func(s *LightState, v interface{}) { s.ColorTemperature = toInt(v) }})
+	}
+	if d.propColor.valid {
+		fields = append(fields, field{d.propColor.siid, d.propColor.piid, "color",
+			func(s *LightState, v interface{}) {
+				if v, ok := v.(float64); ok {
+					c := int(v)
+					s.ColorRGB = [3]int{(c >> 16) & 0xFF, (c >> 8) & 0xFF, c & 0xFF}
+				}
+			}})
+	}
+	if len(fields) == 0 {
 		return "", xiaomi.ErrNotSupported
 	}
-	return d.SubProp(d.propOn.siid, d.propOn.piid, func(did string, prop *xiaomi.PropertyValue) {
-		state := LightState{}
-		if b, ok := prop.Value.(bool); ok {
-			state.Power = b
+	return d.SubProp(0, 0, func(did string, prop *xiaomi.PropertyValue) {
+		for _, f := range fields {
+			if f.siid == prop.SIID && f.piid == prop.PIID {
+				f.fill(&d.stateCache, prop.Value)
+				handler(d.stateCache, f.name)
+				return
+			}
 		}
-		handler(state)
 	})
 }