chore: corrected misleading error descriptions, removed redundant comments

backend/internal/utils/security.go

@@ -45,7 +45,7 @@ func ValidatePassword(password string) error {
 
 	if cfg.PasswordCheckCases {
 		differentCasesPresent := regexp.MustCompile(`(?=.*[a-z])(?=.*[A-Z])`).MatchString(password); if !differentCasesPresent {
-			return errors.New("Password must contain at least 1 number")
+			return errors.New("Password must have uppercase and lowercase characters")
 		}
 	}