接入首页位置上报与在线倒计时，并优化上报交互体验。

持久化服务端 expired 过期时间戳以正确恢复倒计时，切换在线/离线与上报时展示定位 Loading，移除重复的成功 Alert，并将 Toast 调整为居中半透明样式。

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

suixinkan/App/State/ToastCenter.swift

@@ -62,18 +62,17 @@ final class ToastCenter: ObservableObject {
     #endif
 }
 
-/// 全局 Toast 叠加层修饰器，负责把 Toast 展示到页面顶部。
+/// 全局 Toast 叠加层修饰器，负责把 Toast 展示到屏幕中央。
 private struct GlobalToastOverlay: ViewModifier {
     @EnvironmentObject private var toastCenter: ToastCenter
 
     func body(content: Content) -> some View {
         content
-            .overlay(alignment: .top) {
-                GeometryReader { proxy in
+            .overlay {
+                Group {
                     if let message = toastCenter.message {
-                        toastBanner(message, topInset: proxy.safeAreaInsets.top)
-                            .transition(.move(edge: .top).combined(with: .opacity))
-                            .frame(maxWidth: .infinity, maxHeight: .infinity, alignment: .top)
+                        toastBanner(message)
+                            .transition(.opacity)
                     }
                 }
                 .allowsHitTesting(false)
@@ -81,22 +80,23 @@ private struct GlobalToastOverlay: ViewModifier {
             .animation(.easeInOut(duration: 0.18), value: toastCenter.message)
     }
 
-    /// 构建顶部全宽 Toast 横幅。
-    private func toastBanner(_ message: String, topInset: CGFloat) -> some View {
-        HStack {
+    /// 构建屏幕中央的黑色半透明圆角 Toast 卡片。
+    private func toastBanner(_ message: String) -> some View {
+        HStack(spacing: 10) {
+            Image(systemName: "exclamationmark.triangle.fill")
+                .font(.system(size: 16, weight: .semibold))
+
             Text(message)
-                .font(.system(size: 14, weight: .medium))
-                .lineLimit(2)
-                .multilineTextAlignment(.center)
+                .font(.system(size: 16, weight: .medium))
+                .lineLimit(3)
+                .multilineTextAlignment(.leading)
                 .fixedSize(horizontal: false, vertical: true)
-                .frame(maxWidth: .infinity, alignment: .center)
         }
         .foregroundStyle(.white)
-        .padding(.horizontal, AppMetrics.Spacing.pageHorizontal)
-        .padding(.top, topInset + AppMetrics.Spacing.small)
-        .padding(.bottom, AppMetrics.Spacing.small)
-        .frame(maxWidth: .infinity, alignment: .center)
-        .background(AppDesign.primary.ignoresSafeArea(edges: .top))
+        .padding(.horizontal, 20)
+        .padding(.vertical, 14)
+        .background(Color.black.opacity(0.78), in: RoundedRectangle(cornerRadius: 12))
+        .padding(.horizontal, 40)
     }
 }