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/state/inventory_cubit_test.dart

@@ -103,6 +103,20 @@ void main() {
     expect(cubit.state.visibleItems.single.label, 'Tired');
   });
 
+  test('sharing filter keeps only varieties with an offered lot', () async {
+    final sharedId = await repo.addQuickVariety(label: 'Shared');
+    await repo.addLot(varietyId: sharedId, offerStatus: OfferStatus.shared);
+    final privateId = await repo.addQuickVariety(label: 'Private');
+    await repo.addLot(varietyId: privateId);
+    await waitFor(cubit, (s) => s.hasShared && s.items.length == 2);
+
+    cubit.toggleSharingOnly();
+    expect(cubit.state.visibleItems.single.label, 'Shared');
+
+    cubit.toggleSharingOnly();
+    expect(cubit.state.visibleItems, hasLength(2));
+  });
+
   test('clearFilters resets every filter but keeps the search query', () async {
     await repo.addQuickVariety(label: 'Maize', category: 'Poaceae');
     await waitFor(cubit, (s) => s.items.isNotEmpty);
@@ -112,13 +126,15 @@ void main() {
       ..toggleCategory('Poaceae')
       ..toggleType(LotType.seed)
       ..toggleOrganicOnly()
-      ..toggleNeedsReproductionOnly();
+      ..toggleNeedsReproductionOnly()
+      ..toggleSharingOnly();
     cubit.clearFilters();
 
     expect(cubit.state.categoryFilter, isEmpty);
     expect(cubit.state.typeFilter, isEmpty);
     expect(cubit.state.organicOnly, isFalse);
     expect(cubit.state.needsReproductionOnly, isFalse);
+    expect(cubit.state.sharingOnly, isFalse);
     expect(cubit.state.query, 'mai');
   });