基于 Lottie 在关键流程中新增全局 Loading 遮罩

引入带引用计数的 GlobalLoadingCenter，通过 RootView 及主要登录/订单/个人中心页面接入，并添加 Loading 动画资源与单元测试。

Co-authored-by: Cursor <cursoragent@cursor.com>

suixinkan/Features/Auth/Views/AccountSelectionView.swift

@@ -71,15 +71,9 @@ struct AccountSelectionView: View {
                 guard let selectedAccount else { return }
                 onConfirm(selectedAccount)
             } label: {
-                HStack(spacing: AppMetrics.Spacing.xSmall) {
-                    if isLoading {
-                        ProgressView()
-                            .tint(.white)
-                    }
-                    Text("进入系统")
-                        .font(.system(size: AppMetrics.FontSize.body, weight: .semibold))
-                }
-                .foregroundStyle(.white)
+                Text("进入系统")
+                    .font(.system(size: AppMetrics.FontSize.body, weight: .semibold))
+                    .foregroundStyle(.white)
                 .frame(maxWidth: .infinity)
                 .frame(height: AppMetrics.ControlSize.primaryButtonHeight)
                 .background(canConfirm ? AppDesign.primary : Color(hex: 0xC9CED6), in: RoundedRectangle(cornerRadius: AppMetrics.CornerRadius.button))