feat: add setUserInfo/clearUserInfo to XuqmCoreSDK, align with Android API

Co-Authored-By: Claude <noreply@anthropic.com>

Sources/XuqmCoreSDK/XuqmSDK.swift

@@ -48,6 +48,8 @@ public final class XuqmSDK: NSObject {
     public private(set) var tokenStore: TokenStore?
 
     public private(set) var currentUserId: String?
+    public private(set) var currentNickname: String?
+    public private(set) var currentAvatar: String?
 
     private var userSig: String?
     public private(set) var cachedDeviceToken: String?
@@ -155,6 +157,25 @@ public final class XuqmSDK: NSObject {
         cachedDeviceToken = nil
     }
 
+    /// 设置用户信息（登录后调用）
+    /// 用于灰度发布、精准推送等场景
+    /// - Parameters:
+    ///   - userId: 用户唯一标识
+    ///   - nickname: 用户昵称（可选）
+    ///   - avatar: 用户头像 URL（可选）
+    public func setUserInfo(userId: String, nickname: String? = nil, avatar: String? = nil) {
+        self.currentUserId = userId
+        self.currentNickname = nickname
+        self.currentAvatar = avatar
+    }
+
+    /// 清除用户信息（登出时调用）
+    public func clearUserInfo() {
+        self.currentUserId = nil
+        self.currentNickname = nil
+        self.currentAvatar = nil
+    }
+
     public func registerDeviceToken(_ deviceToken: Data) {
         let token = deviceToken.map { String(format: "%02x", $0) }.joined()
         self.cachedDeviceToken = token