refactor(tui): consistent chrome across all views

- Extract divider() and emptyState() helpers to format.go
- All empty states now use bordered box with accent color
- Detail and alert detail panels get header/section dividers
- SLA label width 14→16 to match detail/alert panels
- Logs key hints moved from content to dashboard footer
- History/SLA panels use shared divider helper

internal/tui/format.go

@@ -2,11 +2,37 @@ package tui
 
 import (
 	"fmt"
+	"strings"
 	"time"
 
 	"gitea.lerkolabs.com/lerkolabs/uptop/internal/models"
+	"github.com/charmbracelet/lipgloss"
 )
 
+func (m Model) dividerWidth() int {
+	w := m.termWidth - chromePadH - 4
+	if w < 40 {
+		w = 40
+	}
+	return w
+}
+
+func (m Model) divider() string {
+	return "  " + subtleStyle.Render(strings.Repeat("─", m.dividerWidth()))
+}
+
+func (m Model) emptyState(message, hint string) string {
+	content := message
+	if hint != "" {
+		content += "\n\n" + subtleStyle.Render(hint)
+	}
+	return "\n" + lipgloss.NewStyle().
+		Border(lipgloss.RoundedBorder()).
+		BorderForeground(m.theme.Accent).
+		Padding(1, 3).
+		Render(content)
+}
+
 func limitStr(text string, max int) string {
 	runes := []rune(text)
 	if len(runes) > max {