feat(tui): mouse click for settings sections, column sort, logs panel

- Click Alerts/Nodes/Users sub-tabs in settings to switch sections
- Click STATUS/NAME/LATENCY column headers to sort (click again
  to reverse direction)
- Logs panel show/hide: [l] toggles sidebar visibility, click
  focused panel to hide. Monitors expand to full width when hidden.
- Logs full-screen: Enter when focused on logs opens scrollable
  full-screen log view with severity tags, filter toggle [f],
  and live updates

internal/tui/tui.go

@@ -197,6 +197,7 @@ type Model struct {
 	lastTabLoad        time.Time // last dispatch of loadTabDataCmd (throttle)
 	tabSeq             int       // seq of the newest issued tab-data load
 
+	logsOpen            bool
 	detailOpen          bool
 	detailChanges       []models.StateChange
 	detailChangesSiteID int
@@ -247,6 +248,7 @@ func InitialModel(ctx context.Context, isAdmin bool, s store.Store, eng *monitor
 		theme:           theme,
 		themeIndex:      themeIdx,
 		st:              newStyles(theme),
+		logsOpen:        true,
 		detailOpen:      detailPref == "true",
 		demoMode:        os.Getenv("UPTOP_DEMO") == "1",
 		version:         version,