feat: show Anonymous in league when name empty, add username to settings, show salary hint in summary

internal/bot/summary.go

@@ -114,6 +114,8 @@ func (h *Handler) buildMonthlySummary(user *db.User, calY, calM int, startStr, e
 		est := computeMonthlySalary(days, h.DB, user.ID, st.HourlyRate, loc)
 		b.WriteString(fmt.Sprintf("\nSalary: %s (%.1f hours, %d days)",
 			est.formatSalary(st.Currency), est.WorkHours, est.WorkDays))
+	} else {
+		b.WriteString("\nSalary: No rate configured — use /setrate <amount>")
 	}
 
 	b.WriteString("\n\nDetails:\n")