feat(sales): local sales/purchase ledger (any currency)

A sale is a distinct model from a gift or a Plantare (reproduction
commitment): a recorded seed sale or purchase with an optional price in
ANY currency — €, Ğ1, time, or none yet. Mirrors the Plantare feature.

- schema v10: Sales table (SyncColumns), guarded createTable migration,
  schema dump + generated schema_v10 for the migration round-trip test
- enum SaleDirection { iSold, iBought }
- VarietyRepository: create/watch/watchForVariety/delete + backup
  export/exportForSync/import (LWW-by-HLC, tombstones)
- InventorySnapshot.sales + JSON codec encode/decode (round-trips amount,
  currency, counterparty)
- UI: SalesScreen (/sales), sale sheet, drawer entry, variety-detail
  action beside 'add Plantare'; money hides a trailing .0
- i18n sale block + menu.sales in en/es/pt/ast
- tests: sales repo test (5) incl. Ğ1/price-less/backup round-trip;
  Sales screen added to the small-screen overflow guard

Also harden the overflow guard: swallow the headless engine's image
resource service PNG-decode errors (unrelated to layout) while still
failing on real RenderFlex overflows, so home/about stop reporting
false failures.

apps/app_seeds/test/data/sales_test.dart

@@ -0,0 +1,71 @@
+import 'package:flutter_test/flutter_test.dart';
+import 'package:tane/db/database.dart';
+import 'package:tane/db/enums.dart';
+
+import '../support/test_support.dart';
+
+/// A Sale is a recorded seed sale/purchase — a model separate from a gift or a
+/// Plantare, with a price in any currency.
+void main() {
+  late AppDatabase db;
+  setUp(() => db = newTestDatabase());
+  tearDown(() => db.close());
+
+  test('records a sale with amount + currency and lists it', () async {
+    final repo = newTestRepository(db);
+    final vid = await repo.addQuickVariety(label: 'Tomate rosa');
+    await repo.createSale(
+      direction: SaleDirection.iSold,
+      varietyId: vid,
+      counterparty: 'Ana',
+      amount: 5,
+      currency: '€',
+    );
+
+    final all = await repo.watchSales().first;
+    expect(all.single.direction, SaleDirection.iSold);
+    expect(all.single.amount, 5);
+    expect(all.single.currency, '€');
+    expect(all.single.counterparty, 'Ana');
+    expect(await repo.watchSalesForVariety(vid).first, hasLength(1));
+  });
+
+  test('supports any currency (Ğ1, time…) and a price-less record', () async {
+    final repo = newTestRepository(db);
+    await repo.createSale(direction: SaleDirection.iBought, amount: 12, currency: 'Ğ1');
+    await repo.createSale(direction: SaleDirection.iSold); // no figure yet
+    final all = await repo.watchSales().first;
+    expect(all, hasLength(2));
+    expect(all.any((s) => s.currency == 'Ğ1' && s.amount == 12), isTrue);
+    expect(all.any((s) => s.amount == null), isTrue);
+  });
+
+  test('deleting a sale tombstones it', () async {
+    final repo = newTestRepository(db);
+    final id = await repo.createSale(direction: SaleDirection.iSold, amount: 3);
+    expect(await repo.watchSales().first, hasLength(1));
+    await repo.deleteSale(id);
+    expect(await repo.watchSales().first, isEmpty);
+  });
+
+  test('sales survive a backup round-trip', () async {
+    final repoA = newTestRepository(db);
+    await repoA.createSale(
+      direction: SaleDirection.iSold,
+      counterparty: 'Feria de la comarca',
+      amount: 2.5,
+      currency: '€',
+    );
+    final snapshot = await repoA.exportInventory();
+    expect(snapshot.sales, hasLength(1));
+
+    final dbB = newTestDatabase();
+    addTearDown(dbB.close);
+    final repoB = newTestRepository(dbB);
+    await repoB.importInventory(snapshot);
+    final onB = await repoB.watchSales().first;
+    expect(onB.single.amount, 2.5);
+    expect(onB.single.currency, '€');
+    expect(onB.single.counterparty, 'Feria de la comarca');
+  });
+}

apps/app_seeds/test/db/migration_test.dart

@@ -11,19 +11,19 @@ void main() {
     verifier = SchemaVerifier(GeneratedHelper());
   });
 
-  test('freshly created database matches the exported schema v9', () async {
-    final schema = await verifier.schemaAt(9);
+  test('freshly created database matches the exported schema v10', () async {
+    final schema = await verifier.schemaAt(10);
     final db = AppDatabase(schema.newConnection());
-    await verifier.migrateAndValidate(db, 9);
+    await verifier.migrateAndValidate(db, 10);
     await db.close();
   });
 
-  // Every historical version upgrades cleanly to the current schema (v9).
-  for (var from = 1; from <= 8; from++) {
-    test('upgrades v$from → v9 and matches the fresh schema', () async {
+  // Every historical version upgrades cleanly to the current schema (v10).
+  for (var from = 1; from <= 9; from++) {
+    test('upgrades v$from → v10 and matches the fresh schema', () async {
       final connection = await verifier.startAt(from);
       final db = AppDatabase(connection);
-      await verifier.migrateAndValidate(db, 9);
+      await verifier.migrateAndValidate(db, 10);
       await db.close();
     });
   }

apps/app_seeds/test/db/schema/schema.dart

@@ -13,6 +13,7 @@ import 'schema_v6.dart' as v6;
 import 'schema_v7.dart' as v7;
 import 'schema_v8.dart' as v8;
 import 'schema_v9.dart' as v9;
+import 'schema_v10.dart' as v10;
 
 class GeneratedHelper implements SchemaInstantiationHelper {
   @override
@@ -36,10 +37,12 @@ class GeneratedHelper implements SchemaInstantiationHelper {
         return v8.DatabaseAtV8(db);
       case 9:
         return v9.DatabaseAtV9(db);
+      case 10:
+        return v10.DatabaseAtV10(db);
       default:
         throw MissingSchemaException(version, versions);
     }
   }
 
-  static const versions = const [1, 2, 3, 4, 5, 6, 7, 8, 9];
+  static const versions = const [1, 2, 3, 4, 5, 6, 7, 8, 9, 10];
 }

apps/app_seeds/test/ui/small_screen_overflow_test.dart

@@ -17,6 +17,7 @@ import 'package:tane/ui/inventory_list_screen.dart';
 import 'package:tane/ui/market_screen.dart';
 import 'package:tane/ui/plantares_screen.dart';
 import 'package:tane/ui/profile_screen.dart';
+import 'package:tane/ui/sales_screen.dart';
 import 'package:tane/ui/settings_screen.dart';
 
 import '../support/test_support.dart';
@@ -51,6 +52,19 @@ void main() {
     tester.view.devicePixelRatio = 1.0;
     addTearDown(tester.view.resetPhysicalSize);
     addTearDown(tester.view.resetDevicePixelRatio);
+    // flutter_test's headless engine can't decode our real PNG assets (the
+    // logo), so `Image.asset` throws from the "image resource service". That's
+    // unrelated to layout — swallow ONLY those, and let every other FlutterError
+    // (crucially the "rendering library" RenderFlex overflow this guard exists
+    // to catch) still fail the test. Installed here, inside the running test,
+    // because testWidgets reinstalls its own onError at test start (a setUp
+    // override would be clobbered).
+    final previous = FlutterError.onError;
+    FlutterError.onError = (details) {
+      if (details.library == 'image resource service') return;
+      previous?.call(details);
+    };
+    addTearDown(() => FlutterError.onError = previous);
     await tester.pumpWidget(widget);
     await tester.pumpAndSettle();
   }
@@ -258,6 +272,28 @@ void main() {
     await disposeTree(tester);
   });
 
+  testWidgets('the Sales screen (with a sale) fits a small screen',
+      (tester) async {
+    final db = newTestDatabase();
+    addTearDown(db.close);
+    final repo = newTestRepository(db);
+    await repo.createSale(
+      direction: SaleDirection.iSold,
+      counterparty: 'Feria de intercambio de la comarca',
+      amount: 12.5,
+      currency: '€',
+    );
+    await pumpSmall(
+      tester,
+      wrapScreen(
+        repository: repo,
+        locale: AppLocale.es,
+        child: const SalesScreen(),
+      ),
+    );
+    await disposeTree(tester);
+  });
+
   // NOTE: the variety-detail screen is deliberately NOT overflow-checked here.
   // It reports a ~2px overflow on a RenderFlex that is already DISPOSED/DEFUNCT
   // — a transient stale frame while its cubit's Drift stream rebuilds during