display date in user's selected calendar on main menu and reports

buildStatusText and buildDailyReport now use formatDateForCalendar
to convert the stored Gregorian date to the user's calendar type
(jalali/hijri/gregorian).

internal/bot/dateutil.go

@@ -276,3 +276,17 @@ func parseGregorianDateKey(key string) (int, int, int) {
 	fmt.Sscanf(key, "%04d-%02d-%02d", &y, &m, &d)
 	return y, m, d
 }
+
+func formatDateForCalendar(date, calType string) string {
+	y, m, d := parseGregorianDateKey(date)
+	switch calType {
+	case "jalali":
+		jy, jm, jd := gregorianToJalali(y, m, d)
+		return fmt.Sprintf("%04d-%02d-%02d", jy, jm, jd)
+	case "hijri":
+		hy, hm, hd := gregorianToHijri(y, m, d)
+		return fmt.Sprintf("%04d-%02d-%02d", hy, hm, hd)
+	default:
+		return date
+	}
+}

internal/bot/handlers.go

@@ -350,7 +350,6 @@ func (h *Handler) handleStart(msg *tgbotapi.Message) {
 		return
 	}
 	slog.Info("start", "user_id", user.ID, "chat_id", msg.Chat.ID)
-	h.sendText(msg.Chat.ID, "We hope you have a happy day working.")
 	menu := tgbotapi.NewMessage(msg.Chat.ID, h.buildStatusText(msg.Chat.ID))
 	menu.ReplyMarkup = mainKeyboard()
 	h.Bot.Send(menu)
@@ -1224,7 +1223,7 @@ func (h *Handler) buildStatusText(chatID int64) string {
 		return "Welcome. Choose an action:"
 	}
 
-	text := fmt.Sprintf("Today: %s", day.Date)
+	text := fmt.Sprintf("Today: %s", formatDateForCalendar(day.Date, user.Calendar))
 
 	if day.IsDayOff {
 		text += "\nDay Off"
@@ -1277,16 +1276,16 @@ func (h *Handler) buildDailyReport(user *db.User, day *db.Day, events []db.Event
 
 	if len(events) == 0 {
 		if day.IsDayOff {
-			return fmt.Sprintf("%s - Day Off", day.Date)
+			return fmt.Sprintf("%s - Day Off", formatDateForCalendar(day.Date, user.Calendar))
 		}
-		return fmt.Sprintf("%s - No events recorded.", day.Date)
+		return fmt.Sprintf("%s - No events recorded.", formatDateForCalendar(day.Date, user.Calendar))
 	}
 
 	y, m, d := parseGregorianDateKey(day.Date)
 	dayStart := time.Date(y, time.Month(m), d, 0, 0, 0, 0, loc).Unix()
 	dayEnd := time.Date(y, time.Month(m), d, 23, 59, 59, 0, loc).Unix()
 	totals := ComputeDailyTotals(events, day.MinBreakThreshold, dayStart, dayEnd)
-	lines := fmt.Sprintf("Report for %s", day.Date)
+	lines := fmt.Sprintf("Report for %s", formatDateForCalendar(day.Date, user.Calendar))
 	if day.IsDayOff {
 		lines += "\nDay Off: Yes"
 	}