chore: 提交高层 xiaomi 封装库及示例

- 新增 xiaomi/examples/ 下 8 个示例程序（用户/家庭查询、设备列表、开关/灯光/空调控制、属性订阅、高级过滤分类、SPEC 解析）
- miot_client_sub.go: 重构 SubProp/SubEvent，使用 buildPropTopic/buildEventTopic 支持通配符订阅（siid/piid=0 → +），并修复锁顺序问题（将 RequestRefreshProp 移到 Lock 外）
- spec_parser.go: 新增 downloadSpecFile 方法，本地 SPEC 文件缺失时自动从 miot-spec.org 下载
- ARCH_PLAN.md: 架构设计从 Proposed 更新为 Accepted（v1.0→v1.1），补充设备分类/工厂/SPEC 映射等模块设计
- xiaomi/: 新增 miot 上层强类型封装模块，包含 Client 主入口、用户/家庭/设备 API、属性读写、动作调用、订阅通知，以及 devices/ 设备控制抽象（Switch/Light/AirConditioner/Fan/Cover/Humidifier/Vacuum/WaterHeater/Thermostat）和 specs/ SPEC 查询辅助
- 更多 xiaomi 示例（风扇/窗帘/传感器控制）

xiaomi/devices/cover.go

@@ -0,0 +1,92 @@
+package devices
+
+import (
+	"context"
+	"xiaomihome/xiaomi"
+)
+
+// Cover 窗帘/晾衣架统一控制接口
+type Cover interface {
+	Device
+	Open(ctx context.Context) error
+	Close(ctx context.Context) error
+	Stop(ctx context.Context) error
+
+	SetPosition(ctx context.Context, pct int) error // 0=关, 100=全开
+	GetPosition(ctx context.Context) (int, error)
+}
+
+type coverDevice struct {
+	BaseDevice
+	propMotor    siidPiid // "motor-control" — open/close/stop
+	propPosition siidPiid // "current-position"
+}
+
+const (
+	coverMotorOpen  = 1
+	coverMotorClose = 0
+	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),
+	}
+
+	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
+	}
+	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
+	}
+	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
+	}
+	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
+	}
+	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
+	}
+	prop, err := d.GetProp(ctx, d.propPosition.siid, d.propPosition.piid)
+	if err != nil {
+		return 0, err
+	}
+	return toInt(prop.Value), nil
+}