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/data/variety_repository.dart

@@ -43,6 +43,8 @@ class VarietyDetail extends Equatable {
     required this.label,
     this.category,
     this.notes,
+    this.speciesId,
+    this.scientificName,
     this.lots = const [],
     this.vernacularNames = const [],
     this.photo,
@@ -52,6 +54,8 @@ class VarietyDetail extends Equatable {
   final String label;
   final String? category;
   final String? notes;
+  final String? speciesId;
+  final String? scientificName;
   final List<VarietyLot> lots;
   final List<String> vernacularNames;
   final Uint8List? photo;
@@ -62,6 +66,8 @@ class VarietyDetail extends Equatable {
     label,
     category,
     notes,
+    speciesId,
+    scientificName,
     lots,
     vernacularNames,
     photo,
@@ -202,6 +208,14 @@ class VarietyRepository {
             .getSingleOrNull();
     if (v == null) return null;
 
+    String? scientificName;
+    if (v.speciesId != null) {
+      final species = await (_db.select(
+        _db.species,
+      )..where((s) => s.id.equals(v.speciesId!))).getSingleOrNull();
+      scientificName = species?.scientificName;
+    }
+
     final lots =
         await (_db.select(_db.lots)
               ..where((l) => l.varietyId.equals(id) & l.isDeleted.equals(false))
@@ -227,12 +241,41 @@ class VarietyRepository {
       label: v.label,
       category: v.category,
       notes: v.notes,
+      speciesId: v.speciesId,
+      scientificName: scientificName,
       lots: lots.map(_toLot).toList(),
       vernacularNames: names.map((n) => n.name).toList(),
       photo: photos.isEmpty ? null : photos.first.bytes,
     );
   }
 
+  /// Links [varietyId] to a catalog [speciesId]. If the variety has no category
+  /// yet, prefill it from the species' botanical family (data-model §6).
+  Future<void> linkSpecies(String varietyId, String speciesId) async {
+    final (_, updated) = _stamp();
+    final species = await (_db.select(
+      _db.species,
+    )..where((s) => s.id.equals(speciesId))).getSingleOrNull();
+    final variety = await (_db.select(
+      _db.varieties,
+    )..where((v) => v.id.equals(varietyId))).getSingleOrNull();
+
+    final categoryIsEmpty =
+        variety?.category == null || variety!.category!.trim().isEmpty;
+    final prefill = categoryIsEmpty ? species?.family : null;
+
+    await (_db.update(
+      _db.varieties,
+    )..where((v) => v.id.equals(varietyId))).write(
+      VarietiesCompanion(
+        speciesId: Value(speciesId),
+        category: prefill == null ? const Value.absent() : Value(prefill),
+        updatedAt: Value(updated),
+        lastAuthor: Value(nodeId),
+      ),
+    );
+  }
+
   /// Updates a variety's scalar fields (LWW). Passing null clears [category]
   /// and [notes]; a null [label] leaves the label unchanged.
   Future<void> updateVariety({