feat: responsive TUI layout — mobile/tablet/desktop support

- NEW responsive.go: wrapFooter, adaptiveSidePad, clampWidth, truncateStr
- Footer auto-wraps to multi-line on narrow terminals (full labels preserved)
- Box width clamped to terminal width across all tabs
- Host/key/snippet rows truncated with ellipsis; compact format <35 cols
- SFTP panes stack vertically when terminal < 50 cols
- Tab bar truncates names on overflow
- Form contentW minimum lowered 50->30 for mobile
- Fixed: key_list_tab & snippet_list_tab dropped last data row (off-by-one bug)

pkg/tui/tabs.go

@@ -4,6 +4,7 @@ import (
 	"strings"
 
 	tea "github.com/charmbracelet/bubbletea"
+	"github.com/charmbracelet/lipgloss"
 )
 
 // Tab represents a single tab in the TUI
@@ -182,15 +183,40 @@ func (tm *TabManager) View() string {
 	return b.String()
 }
 
-// renderTabBar renders the top tab bar
+// renderTabBar renders the top tab bar (responsive: truncates names on overflow)
 func renderTabBar(tm *TabManager) string {
 	if len(tm.tabs) == 0 {
 		return ""
 	}
 
+	const cellPad = 4 // Padding(0,2) per tab = 2 left + 2 right
+
+	availW := tm.width - 2
+	if availW < 1 {
+		availW = 1
+	}
+
+	// Measure total width and decide if truncation is needed
+	totalW := 0
+	for _, tab := range tm.tabs {
+		totalW += lipgloss.Width(tab.Name()) + cellPad
+	}
+
+	maxNameW := 0
+	if totalW > availW {
+		perTab := availW / len(tm.tabs)
+		maxNameW = perTab - cellPad
+		if maxNameW < 1 {
+			maxNameW = 1
+		}
+	}
+
 	var cells []string
 	for i, tab := range tm.tabs {
 		name := tab.Name()
+		if maxNameW > 0 && lipgloss.Width(name) > maxNameW {
+			name = truncateStr(name, maxNameW)
+		}
 		if i == tm.active {
 			cells = append(cells, TabActiveStyle.Render(name))
 		} else {