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>

demo/src/main/kotlin/com/duooomi/ble/demo/DemoScreen.kt

@@ -65,7 +65,7 @@ fun DemoScreen(
     val upgradeRecords by sdk.upgradeRecords.collectAsState()
 
     // Editable config (rekey on sdk change so new SDK 不会带着旧编辑残留)
-    var configOwner by remember(sdk) { mutableStateOf(config.owner) }
+    var configBrand by remember(sdk) { mutableStateOf(config.brand) }
     var configApiKey by remember(sdk) { mutableStateOf(config.apiKey) }
     var configScanPrefix by remember(sdk) { mutableStateOf(config.scanPrefix) }
 
@@ -126,14 +126,14 @@ fun DemoScreen(
             // === Config Section ===
             item {
                 SectionHeader("SDK Config（修改后点 Reload 生效）")
-                ConfigField("x-owner", configOwner) { configOwner = it }
+                ConfigField("brand", configBrand) { configBrand = it }
                 ConfigField("apiKey", configApiKey) { configApiKey = it }
                 ConfigField("scanPrefix", configScanPrefix) { configScanPrefix = it }
                 Button(
                     onClick = {
-                        onReload(DemoConfig(configOwner, configApiKey, configScanPrefix))
+                        onReload(DemoConfig(configBrand, configApiKey, configScanPrefix))
                         log(
-                            "SDK reloaded with owner=$configOwner, prefix=$configScanPrefix",
+                            "SDK reloaded with brand=$configBrand, prefix=$configScanPrefix",
                             LogLevel.SUCCESS
                         )
                     },

demo/src/main/kotlin/com/duooomi/ble/demo/MainActivity.kt

@@ -35,7 +35,7 @@ class MainActivity : ComponentActivity() {
 
         val prefs = getSharedPreferences(PREFS, Context.MODE_PRIVATE)
         val initialConfig = DemoConfig(
-            owner = prefs.getString(KEY_OWNER, DemoSecrets.OWNER) ?: DemoSecrets.OWNER,
+            brand = prefs.getString(KEY_BRAND, DemoSecrets.BRAND) ?: DemoSecrets.BRAND,
             apiKey = prefs.getString(KEY_API_KEY, DemoSecrets.API_KEY) ?: DemoSecrets.API_KEY,
             scanPrefix = prefs.getString(KEY_SCAN_PREFIX, DemoSecrets.SCAN_NAME_PREFIX)
                 ?: DemoSecrets.SCAN_NAME_PREFIX
@@ -69,14 +69,14 @@ class MainActivity : ComponentActivity() {
         context = this,
         config = DuooomiBleConfig(
             apiKey = c.apiKey,
-            owner = c.owner,
+            brand = c.brand,
             scanNamePrefix = c.scanPrefix
         )
     )
 
     private fun persist(prefs: SharedPreferences, c: DemoConfig) {
         prefs.edit()
-            .putString(KEY_OWNER, c.owner)
+            .putString(KEY_BRAND, c.brand)
             .putString(KEY_API_KEY, c.apiKey)
             .putString(KEY_SCAN_PREFIX, c.scanPrefix)
             .apply()
@@ -101,14 +101,14 @@ class MainActivity : ComponentActivity() {
 
     private companion object {
         const val PREFS = "demo_config"
-        const val KEY_OWNER = "demo.config.owner"
+        const val KEY_BRAND = "demo.config.brand"
         const val KEY_API_KEY = "demo.config.apiKey"
         const val KEY_SCAN_PREFIX = "demo.config.scanPrefix"
     }
 }
 
 data class DemoConfig(
-    val owner: String,
+    val brand: String,
     val apiKey: String,
     val scanPrefix: String
 )