feat(sdk): 同步 iOS 改动 — owner→brand 重命名 + 硬绑前 brand 校验 + README 内部细节抹除

- DuooomiBleConfig.owner → brand（语义：设备品牌名），HTTP header x-owner 不变
- bind() 前置 verifyBrand：缺 deviceInfo 先 getDeviceInfo，与 config.brand 严格匹配，
  不一致主动 disconnect 并抛 DuooomiBleError.BrandMismatch
- README 抹除软绑/对账/UpgradeRecord 等内部实现细节，仅保留厂商面向的公开 API
  （功能代码完全保留：fetchLatestFirmware 内部三段串、unbind 软解、tryReportPendingUpgrade）
- README 顶部加 demo 优先验证提示

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

sdk/src/main/kotlin/com/duooomi/ble/DuooomiBleSDK.kt

@@ -83,7 +83,7 @@ class DuooomiBleSDK(context: Context, val config: DuooomiBleConfig) {
     private var flushJob: Job? = null
 
     init {
-        BleLog.i("SDK initialized (apiHost=${config.apiHost}, owner=${config.owner})", "SDK")
+        BleLog.i("SDK initialized (apiHost=${config.apiHost}, brand=${config.brand})", "SDK")
         setupDisconnectHandler()
         // 启动时把持久化记录回放到 StateFlow
         _upgradeRecords.value = upgradeRecordStore.all
@@ -253,6 +253,7 @@ class DuooomiBleSDK(context: Context, val config: DuooomiBleConfig) {
      */
     suspend fun bind(userId: String): BindingResponse {
         ensureConnected()
+        verifyBrand()
         BleLog.d("Sending bind (userId=$userId)", "Command")
         val data = sendAndWait(CommandType.BIND_DEVICE) {
             deviceInfoService.bindDevice(userId)
@@ -732,6 +733,19 @@ class DuooomiBleSDK(context: Context, val config: DuooomiBleConfig) {
         }
     }
 
+    /**
+     * 校验设备 brand 与 SDK 配置 brand 是否一致；缺失则先拉一次 deviceInfo。
+     * 不一致时主动断连并抛 [DuooomiBleError.BrandMismatch]。
+     */
+    private suspend fun verifyBrand() {
+        val actual = _deviceInfo.value?.brand ?: getDeviceInfo().brand
+        val expected = config.brand
+        if (actual == expected) return
+        BleLog.w("Brand mismatch: expected=$expected, actual=$actual; disconnecting", "Command")
+        runCatching { disconnect() }
+        throw DuooomiBleError.BrandMismatch(expected = expected, actual = actual)
+    }
+
     private fun parseJsonResponse(data: ByteArray): JSONObject {
         // Device responses may contain null bytes
         val cleaned = data.filter { it != 0.toByte() }.toByteArray()