feat(block1): bundled species catalog + autocomplete link

Add a small curated catalog of Iberian horticultural species and let a variety
be linked to it from the edit sheet.

- assets/catalog/species.json: 14 species with botanical family and ES/EN
  common names (wikidata_qid/gbif_key deferred to the varilla enrichment).
- SpeciesRepository: idempotent seedBundled (is_bundled rows, keyed by
  scientific name) + search by scientific/common name with a locale-best label.
  Seeded on startup from DI.
- VarietyRepository.linkSpecies: sets species_id and prefills category from the
  species' family when empty (never overwrites an existing category).
  VarietyDetail now carries the scientific name.
- Edit sheet gains a live species-search field; the detail view shows the
  scientific name (italic). i18n strings added (ES/EN).

Tests: catalog parse, idempotent seeding, search by scientific/common name,
linkSpecies prefill semantics, and a widget test for the autocomplete → link →
scientific-name-shown flow. Full suite: 32 passing, 0 skipped.

apps/app_seeds/lib/state/variety_detail_cubit.dart

@@ -53,6 +53,9 @@ class VarietyDetailCubit extends Cubit<VarietyDetailState> {
   Future<void> addLot({int? year, Quantity? quantity}) =>
       _repo.addLot(varietyId: varietyId, harvestYear: year, quantity: quantity);
 
+  Future<void> linkSpecies(String speciesId) =>
+      _repo.linkSpecies(varietyId, speciesId);
+
   Future<void> deleteVariety() async {
     await _repo.softDeleteVariety(varietyId);
     emit(