chore: core 多模块骨架

IosClientKit/Sources/CoreUI/LoadingView.swift

@@ -0,0 +1,11 @@
+import SwiftUI
+
+/// 加载中占位视图。
+public struct LoadingView: View {
+    public init() {}
+
+    public var body: some View {
+        ProgressView("加载中…")
+            .frame(maxWidth: .infinity, maxHeight: .infinity)
+    }
+}