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/subscribe_test.go

@@ -0,0 +1,92 @@
+package xiaomi
+
+import "testing"
+
+func TestPropHandler(t *testing.T) {
+	var capturedDID string
+	var capturedProp *PropertyValue
+
+	handler := PropHandler(func(did string, prop *PropertyValue) {
+		capturedDID = did
+		capturedProp = prop
+	})
+
+	handler("test.did", &PropertyValue{
+		DID:   "test.did",
+		SIID:  2,
+		PIID:  1,
+		Value: true,
+	})
+
+	if capturedDID != "test.did" {
+		t.Errorf("captured DID = %q", capturedDID)
+	}
+	if capturedProp == nil {
+		t.Fatal("capturedProp is nil")
+	}
+	if capturedProp.SIID != 2 {
+		t.Errorf("SIID = %d, want 2", capturedProp.SIID)
+	}
+	if b, ok := capturedProp.Value.(bool); !ok || !b {
+		t.Errorf("Value = %v, want true", capturedProp.Value)
+	}
+}
+
+func TestEventHandler(t *testing.T) {
+	var capturedDID string
+	var capturedEvent *EventOccurred
+
+	handler := EventHandler(func(did string, event *EventOccurred) {
+		capturedDID = did
+		capturedEvent = event
+	})
+
+	handler("test.did", &EventOccurred{
+		DID:       "test.did",
+		SIID:      3,
+		EIID:      1,
+		Arguments: map[string]interface{}{"key": "value"},
+		Timestamp: 1234567890,
+	})
+
+	if capturedDID != "test.did" {
+		t.Errorf("captured DID = %q", capturedDID)
+	}
+	if capturedEvent == nil {
+		t.Fatal("capturedEvent is nil")
+	}
+	if capturedEvent.SIID != 3 {
+		t.Errorf("SIID = %d", capturedEvent.SIID)
+	}
+	if v, ok := capturedEvent.Arguments["key"]; !ok || v.(string) != "value" {
+		t.Errorf("Arguments = %v", capturedEvent.Arguments)
+	}
+}
+
+func TestDeviceStateHandler(t *testing.T) {
+	var capturedDID string
+	var capturedState DeviceState
+
+	handler := DeviceStateHandler(func(did string, state DeviceState) {
+		capturedDID = did
+		capturedState = state
+	})
+
+	handler("test.did", StateOnline)
+
+	if capturedDID != "test.did" {
+		t.Errorf("captured DID = %q", capturedDID)
+	}
+	if capturedState != StateOnline {
+		t.Errorf("captured state = %q", capturedState)
+	}
+}
+
+func TestDeviceStateConstants(t *testing.T) {
+	if StateOnline != "online" {
+		t.Errorf("StateOnline = %q", StateOnline)
+	}
+	if StateOffline != "offline" {
+		t.Errorf("StateOffline = %q", StateOffline)
+	}
+}