feat(block1): variety detail + edit screen with reactive lots

Tapping an inventory item now opens its detail (the /variety/:id route was a
placeholder). Read + edit one variety end-to-end:

- Detail view: photo, category, "also known as" names, notes and lots, driven
  by a reactive VarietyDetailCubit.
- Edit core fields (label/category/notes, LWW) via a bottom sheet.
- Add a lot (harvest year + quantity) — the list refreshes reactively.
- Soft-delete (tombstone) with a confirm dialog.

Repository:
- watchVariety(id): merges Drift table-change streams (variety, lots, names,
  attachments) via StreamGroup and reloads the full detail on any change, so a
  lot added to a *different* table still refreshes the view.
- updateVariety (LWW), addLot, softDeleteVariety.

i18n: detail/edit/addLot strings (ES/EN); switched slang to {param} braces
interpolation (translator- and Weblate-friendly).

Tests: repository (reactive watchVariety, update, soft-delete) and widget tests
(render, edit updates title, add-lot appears, delete shows not-found). Full
suite green: 23 passing, 1 skipped (SQLCipher-only encryption guard).

apps/app_seeds/test/support/test_support.dart

@@ -8,6 +8,8 @@ import 'package:tane/data/variety_repository.dart';
 import 'package:tane/db/database.dart';
 import 'package:tane/i18n/strings.g.dart';
 import 'package:tane/state/inventory_cubit.dart';
+import 'package:tane/state/variety_detail_cubit.dart';
+import 'package:tane/ui/variety_detail_screen.dart';
 
 /// A fresh in-memory database for host tests (unencrypted; encryption is
 /// verified separately in the SQLCipher-only security test).
@@ -54,3 +56,30 @@ Widget wrapScreen({
     ),
   );
 }
+
+/// Wraps the [VarietyDetailScreen] for [varietyId] with its cubit + i18n.
+Widget wrapDetail({
+  required VarietyRepository repository,
+  required String varietyId,
+  AppLocale locale = AppLocale.en,
+}) {
+  LocaleSettings.setLocaleSync(locale);
+  return TranslationProvider(
+    child: RepositoryProvider.value(
+      value: repository,
+      child: BlocProvider(
+        create: (_) => VarietyDetailCubit(repository, varietyId),
+        child: MaterialApp(
+          locale: locale.flutterLocale,
+          supportedLocales: AppLocaleUtils.supportedLocales,
+          localizationsDelegates: const [
+            GlobalMaterialLocalizations.delegate,
+            GlobalWidgetsLocalizations.delegate,
+            GlobalCupertinoLocalizations.delegate,
+          ],
+          home: const VarietyDetailScreen(),
+        ),
+      ),
+    ),
+  );
+}