feat(sdk): 重命名 owner→brand 并在硬绑前校验设备品牌

- 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，不一致主动断连并抛 .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）

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

Sources/DuooomiBleSDK/Core/BleTypes.swift

@@ -39,6 +39,7 @@ public enum DuooomiBleError: LocalizedError {
     case permissionDenied
     case unsupportedFormat(String)
     case firmwareUpgradeUnavailable(String)
+    case brandMismatch(expected: String, actual: String)
 
     public var errorDescription: String? {
         switch self {
@@ -76,6 +77,8 @@ public enum DuooomiBleError: LocalizedError {
             return "Unsupported file format: \(ext). Supported: jpeg, png, gif, mp4, webm, webp"
         case .firmwareUpgradeUnavailable(let reason):
             return "Firmware upgrade unavailable: \(reason)"
+        case .brandMismatch(let expected, let actual):
+            return "不支持该品牌设备 (expected=\(expected), actual=\(actual))"
         }
     }
 }