fix(tui): correct delete confirm labels, normalize help text

Delete confirmation dialog used wrong magic numbers for entity kind
mapping — maintenance windows showed as "alert", settings deletions
showed as "monitor". Now uses tab/section constants to match correctly.

Also: consistent [q/Esc] Back across all views, extract detailKeys(),
remove dead maxSections variable, add nodes empty state hint, use
models.Status constants in siteOrder, delete orphaned theme.png.

internal/tui/tab_logs.go

@@ -81,7 +81,7 @@ func (m Model) viewLogsFullscreen() string {
 		filterLabel = m.st.subtleStyle.Render("[f] Important only")
 	}
 	countLabel := m.st.subtleStyle.Render(fmt.Sprintf("%d/%d", m.logShown, m.logTotal))
-	footer := m.divider() + "\n  " + m.st.subtleStyle.Render("[Esc] Back") + "  " + filterLabel + "  " + countLabel
+	footer := m.divider() + "\n  " + m.st.subtleStyle.Render("[q/Esc] Back") + "  " + filterLabel + "  " + countLabel
 
 	m.logViewport.Width = m.termWidth - chromePadH
 	m.logViewport.Height = m.termHeight - 8