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/view_dashboard.go

@@ -266,7 +266,7 @@ func (m Model) renderFooter(stats dashboardStats) string {
 	case 1:
 		keys = "[n]New [e]Edit [i]Info [d]Del [t]Test [T]Theme [Tab]Switch [q]Quit"
 	case 2:
-		keys = "[f]Filter [T]Theme [Tab]Switch [q]Quit"
+		keys = "[↑/↓]Scroll  [PgUp/PgDn]Page  [f]Filter  [T]Theme  [Tab]Switch  [q]Quit"
 	case 4:
 		keys = "[n]New [x]End [d]Del [T]Theme [Tab]Switch [q]Quit"
 	case 5: