feat(inventory): local sharing — per-lot share terms, filter and printable catalog

The local half of the original Fase 2 (no network, no Offer entity yet):
- Lot sheet gains a 'do you share it?' choice (gift/swap first, sale last,
  never the default); declaring plenty of abundance reveals it with a nudge.
- Lot lines and list tiles badge shared batches; an 'I share' filter and
  a printable PDF catalog (paper bridge for fairs) round out the view.
- Catalog PDF embeds DejaVu (Latin-ext/Cyrillic/Greek); fonts are a
  per-locale resource like the OCR packs.

apps/app_seeds/test/data/shared_catalog_test.dart

@@ -0,0 +1,104 @@
+import 'package:commons_core/commons_core.dart';
+import 'package:flutter_test/flutter_test.dart';
+import 'package:tane/data/species_repository.dart';
+import 'package:tane/data/variety_repository.dart';
+import 'package:tane/db/database.dart';
+import 'package:tane/db/enums.dart';
+
+import '../support/test_support.dart';
+
+void main() {
+  late AppDatabase db;
+  late VarietyRepository repo;
+
+  setUp(() {
+    db = newTestDatabase();
+    repo = newTestRepository(db);
+  });
+  tearDown(() => db.close());
+
+  test('addLot and updateLot persist the share terms', () async {
+    final id = await repo.addQuickVariety(label: 'Maize');
+    final lotId = await repo.addLot(
+      varietyId: id,
+      offerStatus: OfferStatus.shared,
+    );
+
+    var detail = await repo.watchVariety(id).first;
+    expect(detail!.lots.single.offerStatus, OfferStatus.shared);
+
+    await repo.updateLot(
+      lotId: lotId,
+      type: LotType.seed,
+      offerStatus: OfferStatus.exchange,
+    );
+    detail = await repo.watchVariety(id).first;
+    expect(detail!.lots.single.offerStatus, OfferStatus.exchange);
+  });
+
+  test('list items flag varieties with some lot offered', () async {
+    final sharedId = await repo.addQuickVariety(label: 'Shared bean');
+    await repo.addLot(varietyId: sharedId, offerStatus: OfferStatus.sell);
+    final privateId = await repo.addQuickVariety(label: 'Private bean');
+    await repo.addLot(varietyId: privateId);
+
+    final items = await repo.watchInventoryView().first;
+    final byLabel = {for (final i in items.items) i.label: i};
+    expect(byLabel['Shared bean']!.isShared, isTrue);
+    expect(byLabel['Private bean']!.isShared, isFalse);
+  });
+
+  test('sharedCatalog lists only offered lots, sorted and joined', () async {
+    final species = newTestSpeciesRepository(db);
+    await species.seedBundled(const [
+      SpeciesSeed(
+        scientificName: 'Zea mays',
+        family: 'Poaceae',
+        commonNames: {
+          'en': ['Maize'],
+        },
+      ),
+    ]);
+
+    final maizeId = await repo.addQuickVariety(label: 'Rebordanes maize');
+    final matches = await species.search('Zea', languageCode: 'en');
+    await repo.linkSpecies(maizeId, matches.single.id);
+    await repo.addLot(
+      varietyId: maizeId,
+      harvestYear: 2024,
+      quantity: const Quantity(kind: QuantityKind.cob, count: 2),
+      offerStatus: OfferStatus.shared,
+    );
+    // A private lot of the same variety stays out of the catalog.
+    await repo.addLot(varietyId: maizeId, harvestYear: 2023);
+
+    final beanId = await repo.addQuickVariety(label: 'Alubia de Tolosa');
+    await repo.addLot(
+      varietyId: beanId,
+      abundance: Abundance.plentyToShare,
+      offerStatus: OfferStatus.exchange,
+    );
+
+    // A deleted shared lot disappears with its tombstone.
+    final goneId = await repo.addQuickVariety(label: 'Gone');
+    final goneLot = await repo.addLot(
+      varietyId: goneId,
+      offerStatus: OfferStatus.shared,
+    );
+    await repo.softDeleteLot(goneLot);
+
+    final catalog = await repo.sharedCatalog();
+    expect(catalog, hasLength(2));
+    // Sorted by label, case-insensitively.
+    expect(catalog.first.varietyLabel, 'Alubia de Tolosa');
+    expect(catalog.first.offerStatus, OfferStatus.exchange);
+    expect(catalog.first.abundance, Abundance.plentyToShare);
+
+    final maize = catalog.last;
+    expect(maize.varietyLabel, 'Rebordanes maize');
+    expect(maize.scientificName, 'Zea mays');
+    expect(maize.category, 'Poaceae');
+    expect(maize.harvestYear, 2024);
+    expect(maize.quantity!.count, 2);
+  });
+}