feat(species): auto-classify variety species from its label

Infer the catalog species a free-text variety label names ("Maiz de la
abuela" -> Zea mays) and prefill the category from the species family.

- Pure, testable matcher (domain/species_autoclassify.dart): whole-word,
  accent/case-insensitive, Unicode-aware (any script), longest-name-wins,
  ambiguous names left unclassified, light plural fold.
- Quick-add and draft naming auto-link the species when the field is empty
  (non-destructive; an explicit category is kept).
- Edit sheet offers a one-tap suggestion from the typed name.

Tests: matcher unit, repository integration, SpeciesRepository.classifyLabel,
and an edit-sheet widget test.

apps/app_seeds/test/ui/variety_detail_screen_test.dart

@@ -76,6 +76,59 @@ void main() {
     await disposeTree(tester);
   });
 
+  testWidgets('typing a name suggests the species and links it on tap', (
+    tester,
+  ) async {
+    final species = newTestSpeciesRepository(db);
+    await species.seedBundled(const [
+      SpeciesSeed(
+        scientificName: 'Zea mays',
+        family: 'Poaceae',
+        commonNames: {
+          'en': ['Maize'],
+          'es': ['Maíz'],
+        },
+      ),
+    ]);
+    final repo = newTestRepository(db);
+    // A label that names no species yet, so nothing is auto-linked on create.
+    final id = await repo.addQuickVariety(label: 'Grandma seed');
+
+    await tester.pumpWidget(
+      wrapDetail(repository: repo, varietyId: id, species: species),
+    );
+    await tester.pumpAndSettle();
+
+    await tester.tap(find.byKey(const Key('detail.edit')));
+    await tester.pumpAndSettle();
+
+    await tester.enterText(
+      find.byKey(const Key('editVariety.name')),
+      'Maize criollo',
+    );
+    await tester.pumpAndSettle();
+
+    // The suggestion surfaces from the typed name.
+    final suggestion = find.byKey(const Key('editVariety.speciesSuggestion'));
+    expect(suggestion, findsOneWidget);
+    expect(find.text('Maize (Zea mays)'), findsOneWidget);
+
+    await tester.tap(suggestion);
+    await tester.pumpAndSettle();
+    // Picking fills the species field with the catalog label.
+    expect(find.text('Maize (Zea mays)'), findsOneWidget);
+
+    final save = find.byKey(const Key('editVariety.save'));
+    await tester.ensureVisible(save);
+    await tester.pumpAndSettle();
+    await tester.tap(save, warnIfMissed: false);
+    await tester.pumpAndSettle();
+
+    // The linked species now shows on the detail header (driven by the stream).
+    expect(find.text('Zea mays'), findsOneWidget);
+    await disposeTree(tester);
+  });
+
   testWidgets('adding a lot shows it in the list', (tester) async {
     final repo = newTestRepository(db);
     final id = await repo.addQuickVariety(label: 'Bean');