Add Telegram notifications for admin on user login

- Create Telegram service for sending notifications
- Send silent notification to @wakeren_bot when user logs in
- Include: username, email, nombre, timestamp
- Notifications only visible to admin (chat ID: 692714536)
- Users are not aware of this feature

backend/internal/services/telegram.go

@@ -0,0 +1,91 @@
+package services
+
+import (
+	"bytes"
+	"encoding/json"
+	"fmt"
+	"net/http"
+	"time"
+)
+
+const (
+	telegramBotToken = "8551922819:AAHIXNbavzcI90eEIGVx1NIisYHecfcBYtU"
+	telegramChatID   = "692714536"
+	telegramAPI      = "https://api.telegram.org/bot"
+)
+
+type TelegramNotification struct {
+	ChatID    string `json:"chat_id"`
+	Text      string `json:"text"`
+	ParseMode string `json:"parse_mode,omitempty"`
+}
+
+type TelegramService struct {
+	client *http.Client
+}
+
+func NewTelegramService() *TelegramService {
+	return &TelegramService{
+		client: &http.Client{
+			Timeout: 10 * time.Second,
+		},
+	}
+}
+
+func (s *TelegramService) SendLoginNotification(username, email, nombre string, timestamp time.Time) error {
+	message := fmt.Sprintf(
+		"🟢 *Nuevo Login - Econ Platform*\n\n"+
+			"👤 *Usuario:* %s\n"+
+			"📧 *Email:* %s\n"+
+			"📝 *Nombre:* %s\n"+
+			"🕐 *Fecha/Hora:* %s\n\n"+
+			"🌐 Plataforma: eco.cbcren.online",
+		username,
+		email,
+		nombre,
+		timestamp.Format("02/01/2006 15:04:05"),
+	)
+
+	return s.sendMessage(message)
+}
+
+func (s *TelegramService) sendMessage(text string) error {
+	url := fmt.Sprintf("%s%s/sendMessage", telegramAPI, telegramBotToken)
+
+	payload := TelegramNotification{
+		ChatID:    telegramChatID,
+		Text:      text,
+		ParseMode: "Markdown",
+	}
+
+	jsonData, err := json.Marshal(payload)
+	if err != nil {
+		return fmt.Errorf("error marshaling telegram payload: %w", err)
+	}
+
+	resp, err := s.client.Post(url, "application/json", bytes.NewBuffer(jsonData))
+	if err != nil {
+		return fmt.Errorf("error sending telegram message: %w", err)
+	}
+	defer resp.Body.Close()
+
+	if resp.StatusCode != http.StatusOK {
+		return fmt.Errorf("telegram API returned status %d", resp.StatusCode)
+	}
+
+	return nil
+}
+
+// SendErrorNotification envía notificación de errores críticos (opcional)
+func (s *TelegramService) SendErrorNotification(errorMsg string) error {
+	message := fmt.Sprintf(
+		"🔴 *Error en Econ Platform*\n\n"+
+			"⚠️ *Error:* %s\n"+
+			"🕐 *Fecha/Hora:* %s\n\n"+
+			"Revisar logs inmediatamente.",
+		errorMsg,
+		time.Now().Format("02/01/2006 15:04:05"),
+	)
+
+	return s.sendMessage(message)
+}