fix(i18n): normalize translations and fallbacks

lib/l10n/display_names.dart

@@ -0,0 +1,29 @@
+import 'gen/app_localizations.dart';
+
+const _legacyAlarmName = 'Alarma musical';
+const _legacyVacationName = 'Vacaciones';
+const _legacyUnnamedStation = 'Sin nombre';
+
+String localizedAlarmName(AppLocalizations l10n, String rawName) {
+  final name = rawName.trim();
+  if (name.isEmpty || name == _legacyAlarmName) {
+    return l10n.defaultAlarmName;
+  }
+  return name;
+}
+
+String localizedVacationName(AppLocalizations l10n, String rawName) {
+  final name = rawName.trim();
+  if (name.isEmpty || name == _legacyVacationName) {
+    return l10n.vacationsDefaultName;
+  }
+  return name;
+}
+
+String localizedStationName(AppLocalizations l10n, String rawName) {
+  final name = rawName.trim();
+  if (name.isEmpty || name == _legacyUnnamedStation) {
+    return l10n.unnamedStation;
+  }
+  return name;
+}