feat: 定义仓库协议与用例（含会话）

IosClientKit/Sources/CoreDomain/ProfileUseCase.swift

@@ -0,0 +1,14 @@
+import CoreModel
+
+/// 获取个人资料的用例。
+public struct ProfileUseCase: Sendable {
+    private let repository: ProfileRepository
+
+    public init(repository: ProfileRepository) {
+        self.repository = repository
+    }
+
+    public func observeProfile() -> AsyncThrowingStream<UserProfile, Error> {
+        repository.observeProfile()
+    }
+}