feat(i18n): add Asturian (asturianu) as a language

Adds Asturianu, translated in full (345 strings), plus the wiring to
make a minority language work end to end — the OS language picker is an
unreliable way to reach it, so the in-app choice must be explicit and
remembered.

- Model Asturian as the real `ast` locale (honest, international-by-design),
  not a fake `es-AST` region — slang rejects a 3-letter region anyway.
- Flutter ships no Material/Cupertino/intl localizations for `ast`, so map
  the framework chrome to Spanish (`materialLocaleFor`); the app's own text
  stays Asturian via slang. Fixes an "Invalid locale ast" crash when the
  auto-backup date was formatted with intl.
- Persist the picked language in the keystore (LocaleStore) and restore it
  at startup so it survives restarts and wins over the device locale.
- Settings: add the Asturianu tile; compare the full AppLocale so `es` and
  `ast` aren't both marked selected.

Tests: LocaleStore round-trip, locale switch + Spanish-chrome fallback,
and a regression for the intl date crash under Asturian.

apps/app_seeds/lib/di/injector.dart

@@ -21,6 +21,7 @@ import '../services/auto_backup_store.dart';
 import '../services/export_import_service.dart';
 import '../services/file_picker_file_service.dart';
 import '../services/file_service.dart';
+import '../services/locale_store.dart';
 import '../services/ocr/label_text_extractor.dart';
 import '../services/ocr/ocr_language.dart';
 import '../services/ocr/tesseract_label_extractor.dart';
@@ -61,9 +62,18 @@ Future<void> configureDependencies() async {
   // contacted here (local-first — the social layer only enriches).
   final socialService = await SocialService.fromRootSeedHex(rootSeedHex);
 
-  // Seed the bundled species catalog (idempotent) before the UI opens.
+  // Seed the bundled species catalog before the UI opens — but only once per
+  // catalog version. Parsing the ~1.5 MB catalog and scanning the species table
+  // on every launch was the main startup jank; the version marker skips both
+  // when this install already holds the current catalog.
+  const catalogVersionKey = 'species_catalog_version';
   final speciesRepository = SpeciesRepository(database, idGen: IdGen());
-  await speciesRepository.seedBundled(await loadBundledSpecies());
+  await speciesRepository.seedBundledIfNeeded(
+    version: speciesCatalogVersion,
+    readVersion: () => secretStore.read(catalogVersionKey),
+    writeVersion: (v) => secretStore.write(catalogVersionKey, v),
+    loadSeeds: loadBundledSpecies,
+  );
 
   final varietyRepository = VarietyRepository(
     database,
@@ -90,6 +100,7 @@ Future<void> configureDependencies() async {
     ..registerSingleton<FileService>(fileService)
     ..registerSingleton<LabelTextExtractor>(labelExtractor)
     ..registerSingleton<OnboardingStore>(OnboardingStore(secretStore))
+    ..registerSingleton<LocaleStore>(LocaleStore(secretStore))
     ..registerSingleton<SocialService>(socialService)
     ..registerSingleton<SocialSettings>(SocialSettings(secretStore))
     ..registerSingleton<OfferOutbox>(OfferOutbox(secretStore))