feat(sdk): OTA 升级流程对齐 expo + 拆 extension 文件分层 + 秘钥本地化

主要改动：
- 新增 fetchLatestFirmware/upgradeFirmware/tryReportPendingUpgrade
  三段 OTA 接口，对齐 expo bindDeviceWithOrchestration 行为
- bind 仅做硬绑+getVersion，软绑/对账上报/拉最新固件搬到
  fetchLatestFirmware 内部串；软绑失败自动硬解回滚
- UpgradeRecord 复合主键 (sn, firmwareId) 持久化 + sn 级 in-flight 互斥
- DuooomiBleSDKDelegate 新增 didUpdateUpgradeRecords，集成方
  可观察对账上报结果（reported/outcome 状态）
- DuooomiBleSDK 主类按职责拆 5 个 extension 文件，公开 API 不变
- TargetFirmware 简化为只取必要字段 + 新增 forceUpgrade
- scanNamePrefix 改为必填 String
- demo 秘钥移至本地 DemoSecrets.swift (gitignored)
- README 重写：完整 OTA 流程示例 + 上报状态判定表

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

Sources/DuooomiBleSDK/Services/DeviceInfoService.swift

@@ -3,9 +3,11 @@ import Foundation
 /// 设备命令服务：发送 JSON 命令（fire-and-forget，响应由协议层回调处理）
 final class DeviceInfoService {
     private let protocolService: BleProtocolService
+    private let timeProvider: BeijingTimeProvider
 
-    init(protocolService: BleProtocolService) {
+    init(protocolService: BleProtocolService, timeProvider: BeijingTimeProvider) {
         self.protocolService = protocolService
+        self.timeProvider = timeProvider
     }
 
     // MARK: - Commands
@@ -24,30 +26,66 @@ final class DeviceInfoService {
         )
     }
 
-    func bindDevice(userId: String) throws {
-        try protocolService.sendJSON(
-            type: .bindDevice,
-            payload: BindPayload(type: CommandType.bindDevice.rawValue, userId: userId, loop: nil)
-        )
+    /// 绑定：先取北京时间再发命令，与 RN 行为对齐。
+    func bindDevice(userId: String, completion: @escaping (Result<Void, Error>) -> Void) {
+        timeProvider.fetch { [weak self] time in
+            guard let self = self else { return }
+            do {
+                try self.protocolService.sendJSON(
+                    type: .bindDevice,
+                    payload: BindPayload(
+                        type: CommandType.bindDevice.rawValue,
+                        userId: userId,
+                        loop: nil,
+                        time: time
+                    )
+                )
+                completion(.success(()))
+            } catch {
+                completion(.failure(error))
+            }
+        }
     }
 
-    func unbindDevice(userId: String) throws {
-        try protocolService.sendJSON(
-            type: .unbindDevice,
-            payload: BindPayload(type: CommandType.unbindDevice.rawValue, userId: userId, loop: nil)
-        )
+    func unbindDevice(userId: String, completion: @escaping (Result<Void, Error>) -> Void) {
+        timeProvider.fetch { [weak self] time in
+            guard let self = self else { return }
+            do {
+                try self.protocolService.sendJSON(
+                    type: .unbindDevice,
+                    payload: BindPayload(
+                        type: CommandType.unbindDevice.rawValue,
+                        userId: userId,
+                        loop: nil,
+                        time: time
+                    )
+                )
+                completion(.success(()))
+            } catch {
+                completion(.failure(error))
+            }
+        }
     }
 
     /// 切换播放模式（复用 BIND_DEVICE 命令字 0x0F，payload 携带 loop 字段）
-    func setPlayMode(userId: String, loop: PlayMode) throws {
-        try protocolService.sendJSON(
-            type: .bindDevice,
-            payload: BindPayload(
-                type: CommandType.bindDevice.rawValue,
-                userId: userId,
-                loop: UInt8(loop.rawValue)
-            )
-        )
+    func setPlayMode(userId: String, loop: PlayMode, completion: @escaping (Result<Void, Error>) -> Void) {
+        timeProvider.fetch { [weak self] time in
+            guard let self = self else { return }
+            do {
+                try self.protocolService.sendJSON(
+                    type: .bindDevice,
+                    payload: BindPayload(
+                        type: CommandType.bindDevice.rawValue,
+                        userId: userId,
+                        loop: UInt8(loop.rawValue),
+                        time: time
+                    )
+                )
+                completion(.success(()))
+            } catch {
+                completion(.failure(error))
+            }
+        }
     }
 
     func deleteFile(key: String) throws {
@@ -77,19 +115,22 @@ private struct CommandPayload: Encodable {
 
 /// 绑定 / 解绑 / 切模式 共用 payload。
 /// `loop == nil` 时严格省略该字段（不写 null），与 Expo 端 zod.optional 行为对齐。
+/// `time` 为北京时间 ISO 8601 字符串。
 struct BindPayload: Encodable {
     let type: UInt8
     let userId: String
     let loop: UInt8?
+    let time: String
 
     enum CodingKeys: String, CodingKey {
-        case type, userId, loop
+        case type, userId, loop, time
     }
 
     func encode(to encoder: Encoder) throws {
         var container = encoder.container(keyedBy: CodingKeys.self)
         try container.encode(type, forKey: .type)
         try container.encode(userId, forKey: .userId)
+        try container.encode(time, forKey: .time)
         if let loop = loop {
             try container.encode(loop, forKey: .loop)
         }