fix: SFTP pane width — account for border in halfW calculation, fix innerW to maxW-2 (padding only), truncate filter line

Root cause: lipgloss Width(maxW) = content area inside border, border adds 2 chars extra.
- halfW was t.width/2, should be t.width/2-2 (reserve border per pane)
- innerW was maxW-4, should be maxW-2 (padding only, not border)
- Each pane total = maxW + 2 (content + border)

pkg/tui/sftp_browser_tab.go

@@ -541,14 +541,19 @@ func (t *SFTPBrowserTab) View() string {
 	}
 
 	// Responsive pane layout: stack vertically on narrow terminals
+	// Each pane renders at maxW+2 total (maxW content + 2 border chars)
 	var leftView, rightView string
 	if t.width < 50 {
-		// Stack vertically — each pane gets full width
-		leftView = t.renderPane(&t.left, paneLocal, t.width)
-		rightView = t.renderPane(&t.right, paneRemote, t.width)
+		// Stack vertically — each pane gets full width minus border
+		paneW := t.width - 2
+		if paneW < 20 {
+			paneW = 20
+		}
+		leftView = t.renderPane(&t.left, paneLocal, paneW)
+		rightView = t.renderPane(&t.right, paneRemote, paneW)
 	} else {
-		// Side by side — each pane gets half width
-		halfW := t.width / 2
+		// Side by side — reserve 2 chars border per pane
+		halfW := t.width/2 - 2
 		if halfW < 20 {
 			halfW = 20
 		}
@@ -601,8 +606,9 @@ func (t *SFTPBrowserTab) renderPane(p *sftpPane, pt paneType, maxW int) string {
 		paneStyle = StylePaneActive
 	}
 
-	// Inner content width: border(2) + padding(2) = 4 overhead
-	innerW := maxW - 4
+	// Inner content width: Width(maxW) sets content area inside border
+	// Padding(0,1) takes 2 chars → inner text = maxW - 2
+	innerW := maxW - 2
 	if innerW < 5 {
 		innerW = 5
 	}
@@ -689,7 +695,11 @@ func (t *SFTPBrowserTab) renderPane(p *sftpPane, pt paneType, maxW int) string {
 	}
 
 	if p.filterMode {
-		content.WriteString("\n" + SubtitleStyle.Render("Filter: "+p.filter+"_"))
+		filterLine := "Filter: " + p.filter + "_"
+		if lipgloss.Width(filterLine) > innerW {
+			filterLine = truncateStr(filterLine, innerW)
+		}
+		content.WriteString("\n" + SubtitleStyle.Render(filterLine))
 	}
 
 	inner := titleBar + "\n" + content.String()