fix: stabilize mobile uploads and show transfer speed

web/src/lib/format.ts

@@ -10,6 +10,18 @@ export function formatSize(bytes: number): string {
   return `${v >= 100 ? v.toFixed(0) : v.toFixed(1)} ${units[i]}`;
 }
 
+export function formatTransferProgress(state: {
+  progress: number;
+  phase?: 'encrypting' | 'uploading';
+  speedBytesPerSecond?: number;
+}): string {
+  const phase = state.phase === 'encrypting' ? '加密中' : state.phase === 'uploading' ? '上传中' : '传输中';
+  const speed = state.speedBytesPerSecond && state.speedBytesPerSecond > 0
+    ? ` · ${formatSize(state.speedBytesPerSecond)}/s`
+    : '';
+  return `${phase} ${Math.round(state.progress * 100)}%${speed}`;
+}
+
 const timeFmt = new Intl.DateTimeFormat('zh-CN', { hour: '2-digit', minute: '2-digit', hour12: false });
 
 export function formatTime(ts: number): string {