add user management functionality with OTP verification and consent handling, DI introduced

internal/phoneutil/phoneutil.go

@@ -0,0 +1,19 @@
+package phoneutil
+
+import (
+	"errors"
+
+	"github.com/nyaruka/phonenumbers"
+)
+
+func ParseAndFormatPhoneNumber(phoneNumber string) (string, error) {
+	parsedNumber, err := phonenumbers.Parse(phoneNumber, "RU")
+	if err != nil {
+		return "", err
+	}
+	result := phonenumbers.Format(parsedNumber, phonenumbers.E164)
+	if result == "" {
+		return "", errors.New("failed to format phone number")
+	}
+	return result, nil
+}