feat(labels): choose copies per label, prefilled from container count

Each label in the print sheet gets an editable copy count, suggested from
the lot's latest condition-check container count (3 jars → 3 labels), and
falling back to 1. Type or step the count; the total updates live and Save
is disabled at zero. On save each seed expands into that many identical
labels.

- SeedLabelEntry.suggestedCopies; labelRows reads the latest container count
- label print sheet: per-row −/number/+ stepper, live total, expand on save
- tests: repository suggestedCopies + print-sheet copy chooser

apps/app_seeds/test/data/variety_repository_test.dart

@@ -132,5 +132,26 @@ void main() {
       final rows = await repo.labelRows({selected}, languageCode: 'en');
       expect(rows.map((r) => r.varietyLabel), ['Selected']);
     });
+
+    test('suggests copies from the latest container count', () async {
+      final v = await repo.addQuickVariety(label: 'Tomate');
+      final withJars = await repo.addLot(varietyId: v, harvestYear: 2024);
+      final noCheck = await repo.addLot(varietyId: v, harvestYear: 2025);
+      // Two checks on the same lot: the most recent (3 jars) wins.
+      await repo.addConditionCheck(lotId: withJars, checkedOn: 1, containerCount: 2);
+      await repo.addConditionCheck(lotId: withJars, checkedOn: 2, containerCount: 3);
+
+      final rows = await repo.labelRows({v}, languageCode: 'en');
+      final byYear = {for (final r in rows) r.harvestYear: r};
+      expect(byYear[2024]!.suggestedCopies, 3); // latest check
+      expect(byYear[2025]!.suggestedCopies, 1); // no check → default 1
+      expect(noCheck, isNotEmpty);
+    });
+
+    test('a variety with no lots suggests a single copy', () async {
+      final v = await repo.addQuickVariety(label: 'Alubia');
+      final rows = await repo.labelRows({v}, languageCode: 'en');
+      expect(rows.single.suggestedCopies, 1);
+    });
   });
 }