fix: currency validation, league mobile layout, settings 2-col, burnout ratio, add setusername

- Require both symbol+code in /setcurrency; add preset picker ($ USD,
  T Toman, IRR Rial, EUR, GBP) in settings inline menu
- League: compact 2-line per entry for mobile; sort buttons in 2x2 grid
- Settings: 2-column layout with grouped buttons (timezone+calendar,
  report+report time, break+accent, rpg+league, currency+rate)
- Burnout: cap break ratio at 100% to prevent nonsense values
- Add /setusername command (uses existing SanitizeDisplayName)
- Update /help with new/changed commands

internal/bot/league.go

@@ -18,7 +18,7 @@ const (
 	LeagueSortHours  LeagueSortOption = "hours"
 )
 
-// buildLeagueText returns the formatted league rankings.
+// buildLeagueText returns the formatted league rankings (mobile-friendly narrow layout).
 func (h *Handler) buildLeagueText(orderBy LeagueSortOption) string {
 	entries, err := h.DB.GetLeagueRankings(string(orderBy))
 	if err != nil {
@@ -33,37 +33,15 @@ func (h *Handler) buildLeagueText(orderBy LeagueSortOption) string {
 		"xp":     "XP",
 		"level":  "Level",
 		"streak": "Streak",
-		"hours":  "Total Hours",
+		"hours":  "Hours",
 	}
-	b.WriteString(fmt.Sprintf("WorkTime League — sorted by %s\n\n", orderLabel[string(orderBy)]))
-
-	// Determine column widths
-	maxUserLen := 0
-	for _, e := range entries {
-		l := len(e.Username)
-		if l > maxUserLen {
-			maxUserLen = l
-		}
-	}
-	if maxUserLen < 8 {
-		maxUserLen = 8
-	}
-	if maxUserLen > 20 {
-		maxUserLen = 20
-	}
-
-	header := fmt.Sprintf("%-3s %-*s %8s %6s %6s %12s", "#", maxUserLen, "Username", "XP", "Level", "Streak", "Hours")
-	b.WriteString(header + "\n")
-	b.WriteString(strings.Repeat("-", len(header)) + "\n")
+	b.WriteString(fmt.Sprintf("WorkTime League — %s\n\n", orderLabel[string(orderBy)]))
 
 	for i, e := range entries {
 		rank := i + 1
 		name := e.Username
-		if len(name) > maxUserLen {
-			name = name[:maxUserLen]
-		}
-		b.WriteString(fmt.Sprintf("%-3d %-*s %8d %6d %6d %12.1f\n",
-			rank, maxUserLen, name, e.XP, e.Level, e.Streak, e.TotalHours))
+		b.WriteString(fmt.Sprintf("%d  %s\n", rank, name))
+		b.WriteString(fmt.Sprintf("    XP:%d  Lv:%d  S:%d  %.1fh\n", e.XP, e.Level, e.Streak, e.TotalHours))
 	}
 
 	b.WriteString(fmt.Sprintf("\n%d participant(s)\n", len(entries)))
@@ -128,12 +106,13 @@ func (h *Handler) handleLeagueCallback(ctx context.Context, chatID int64, msgID
 	h.editText(ctx, chatID, msgID, text, &kb)
 }
 
-// buildLeagueKeyboard creates the league navigation keyboard.
+// buildLeagueKeyboard creates the league navigation keyboard (2x2 sort grid).
 func (h *Handler) buildLeagueKeyboard(currentOrder string) models.InlineKeyboardMarkup {
-	orders := []struct {
+	type sortBtn struct {
 		label string
 		data  string
-	}{
+	}
+	orders := []sortBtn{
 		{"XP", "league_xp"},
 		{"Level", "league_level"},
 		{"Streak", "league_streak"},
@@ -141,14 +120,16 @@ func (h *Handler) buildLeagueKeyboard(currentOrder string) models.InlineKeyboard
 	}
 
 	rows := [][]models.InlineKeyboardButton{}
-	for _, o := range orders {
-		label := o.label
-		if o.data == "league_"+currentOrder {
-			label = "> " + label
+	for i := 0; i < len(orders); i += 2 {
+		row := []models.InlineKeyboardButton{}
+		for j := i; j < i+2 && j < len(orders); j++ {
+			label := orders[j].label
+			if orders[j].data == "league_"+currentOrder {
+				label = "> " + label
+			}
+			row = append(row, models.InlineKeyboardButton{Text: label, CallbackData: orders[j].data})
 		}
-		rows = append(rows, []models.InlineKeyboardButton{
-			{Text: label, CallbackData: o.data},
-		})
+		rows = append(rows, row)
 	}
 	rows = append(rows, []models.InlineKeyboardButton{
 		{Text: "Back to Menu", CallbackData: "back_menu"},