feat: SFTP file transfer progress bar + auto-refresh

- Progress bar: [████████░░░░] 67% 12.3MB/18.5MB
- progressWriter wraps io.Writer, reports bytes via callback
- Footer shows live progress during upload/download
- Auto-refresh destination pane after transfer completes
- Success message shown for 1 second before clearing

pkg/tui/sftp_browser_tab.go

@@ -425,27 +425,59 @@ func (t *SFTPBrowserTab) Update(msg tea.Msg) (Tab, tea.Cmd) {
 }
 
 func (t *SFTPBrowserTab) copyFile(srcType, dstType paneType, srcPath, dstPath, name string) {
+	// Get file size for progress bar
+	var totalSize int64
+	if srcType == paneRemote {
+		t.mu.Lock()
+		client := t.right.sftpClient
+		t.mu.Unlock()
+		if client != nil {
+			if info, err := client.Stat(srcPath); err == nil {
+				totalSize = info.Size()
+			}
+		}
+	} else {
+		if info, err := os.Stat(srcPath); err == nil {
+			totalSize = info.Size()
+		}
+	}
+
 	t.mu.Lock()
 	t.transferring = true
-	t.transferMsg = fmt.Sprintf("Copying %s...", name)
+	t.transferMsg = fmt.Sprintf("Copying %s... 0%%", name)
 	t.mu.Unlock()
 
+	progressFn := func(transferred int64) {
+		if totalSize <= 0 {
+			return
+		}
+		pct := int(transferred * 100 / totalSize)
+		barWidth := 20
+		filled := int(float64(barWidth) * float64(transferred) / float64(totalSize))
+		if filled > barWidth {
+			filled = barWidth
+		}
+		bar := strings.Repeat("█", filled) + strings.Repeat("░", barWidth-filled)
+		t.mu.Lock()
+		t.transferMsg = fmt.Sprintf("Copying %s... [%s] %d%% %s/%s",
+			name, bar, pct, formatSize(transferred), formatSize(totalSize))
+		t.mu.Unlock()
+	}
+
 	var err error
 	if srcType == paneRemote && dstType == paneLocal {
-		// Download
 		t.mu.Lock()
 		client := t.right.sftpClient
 		t.mu.Unlock()
 		if client != nil {
-			err = downloadFile(client, srcPath, dstPath)
+			err = downloadFile(client, srcPath, dstPath, progressFn)
 		}
 	} else if srcType == paneLocal && dstType == paneRemote {
-		// Upload
 		t.mu.Lock()
 		client := t.right.sftpClient
 		t.mu.Unlock()
 		if client != nil {
-			err = uploadFile(client, srcPath, dstPath)
+			err = uploadFile(client, srcPath, dstPath, progressFn)
 		}
 	}
 
@@ -453,19 +485,26 @@ func (t *SFTPBrowserTab) copyFile(srcType, dstType paneType, srcPath, dstPath, n
 	if err != nil {
 		t.err = fmt.Errorf("copy %s: %w", name, err)
 	} else {
-		t.transferMsg = ""
+		t.transferMsg = fmt.Sprintf("Done: %s", name)
 	}
 	t.transferring = false
 	t.mu.Unlock()
 
+	// Auto-refresh destination pane
 	if dstType == paneRemote {
 		t.refreshRemote()
 	} else {
 		t.refreshLocal()
 	}
+
+	// Clear success message after brief delay
+	time.Sleep(1 * time.Second)
+	t.mu.Lock()
+	t.transferMsg = ""
+	t.mu.Unlock()
 }
 
-func downloadFile(client *sftp.Client, remotePath, localPath string) error {
+func downloadFile(client *sftp.Client, remotePath, localPath string, progressFn func(int64)) error {
 	src, err := client.Open(remotePath)
 	if err != nil {
 		return err
@@ -478,11 +517,12 @@ func downloadFile(client *sftp.Client, remotePath, localPath string) error {
 	}
 	defer dst.Close()
 
-	_, err = io.Copy(dst, src)
+	pw := &progressWriter{w: dst, total: 0, fn: progressFn}
+	_, err = io.Copy(pw, src)
 	return err
 }
 
-func uploadFile(client *sftp.Client, localPath, remotePath string) error {
+func uploadFile(client *sftp.Client, localPath, remotePath string, progressFn func(int64)) error {
 	src, err := os.Open(localPath)
 	if err != nil {
 		return err
@@ -495,10 +535,27 @@ func uploadFile(client *sftp.Client, localPath, remotePath string) error {
 	}
 	defer dst.Close()
 
-	_, err = io.Copy(dst, src)
+	pw := &progressWriter{w: dst, total: 0, fn: progressFn}
+	_, err = io.Copy(pw, src)
 	return err
 }
 
+// progressWriter wraps an io.Writer and reports progress via callback
+type progressWriter struct {
+	w     io.Writer
+	total int64
+	fn    func(int64)
+}
+
+func (pw *progressWriter) Write(p []byte) (int, error) {
+	n, err := pw.w.Write(p)
+	pw.total += int64(n)
+	if pw.fn != nil {
+		pw.fn(pw.total)
+	}
+	return n, err
+}
+
 func (t *SFTPBrowserTab) deleteItem(fullPath string, isDir bool, isRemote bool) {
 	t.mu.Lock()
 	t.transferring = true