feat(shell): home menu + navigation drawer (mockups 02/03)

The app now opens on a main menu instead of straight into the list:
- HomeScreen (mockup 02): sprout logo over a faint seed-glyph watermark, with
  big "Your inventory" (→ /inventory) and "Open market" (Block 2, "coming soon")
  destinations.
- AppDrawer (mockup 03): Inventory is live; the social items (market, profile,
  chat, wishlist, following, settings) are shown disabled with a "coming soon"
  tag so the roadmap is visible. Drawer is available on home and inventory.
- Routing: / → home, /inventory → list, /variety/:id → detail.

Tests: home shows the menu + navigates; drawer opens + navigates. quick-add flow
updated to go home → inventory. 50 green; Linux runs.

apps/app_seeds/test/ui/home_screen_test.dart

@@ -0,0 +1,55 @@
+import 'package:flutter/material.dart';
+import 'package:flutter_test/flutter_test.dart';
+import 'package:tane/app.dart';
+import 'package:tane/i18n/strings.g.dart';
+
+import '../support/test_support.dart';
+
+void main() {
+  Widget app(db) => TranslationProvider(
+    child: TaneApp(
+      repository: newTestRepository(db),
+      species: newTestSpeciesRepository(db),
+    ),
+  );
+
+  testWidgets('home shows the menu and navigates to inventory', (tester) async {
+    LocaleSettings.setLocaleSync(AppLocale.en);
+    final db = newTestDatabase();
+    addTearDown(db.close);
+
+    await tester.pumpWidget(app(db));
+    await tester.pumpAndSettle();
+
+    expect(find.text('Your inventory'), findsOneWidget);
+    expect(find.text('Open market'), findsOneWidget);
+    expect(find.text('Coming soon'), findsOneWidget); // market is Block 2
+
+    await tester.tap(find.byKey(const Key('home.inventory')));
+    await tester.pumpAndSettle();
+
+    expect(find.text('No seeds yet. Tap + to add your first.'), findsOneWidget);
+    await disposeTree(tester);
+  });
+
+  testWidgets('drawer opens and its Inventory item navigates', (tester) async {
+    LocaleSettings.setLocaleSync(AppLocale.en);
+    final db = newTestDatabase();
+    addTearDown(db.close);
+
+    await tester.pumpWidget(app(db));
+    await tester.pumpAndSettle();
+
+    await tester.tap(find.byIcon(Icons.menu)); // hamburger
+    await tester.pumpAndSettle();
+
+    // Social destinations are shown but disabled.
+    expect(find.text('Your profile'), findsOneWidget);
+
+    await tester.tap(find.text('Inventory')); // active drawer item
+    await tester.pumpAndSettle();
+
+    expect(find.text('No seeds yet. Tap + to add your first.'), findsOneWidget);
+    await disposeTree(tester);
+  });
+}

apps/app_seeds/test/ui/quick_add_flow_test.dart

@@ -24,6 +24,10 @@ void main() {
       );
       await tester.pumpAndSettle();
 
+      // Home → inventory.
+      await tester.tap(find.byKey(const Key('home.inventory')));
+      await tester.pumpAndSettle();
+
       // Starts empty.
       expect(
         find.text('No seeds yet. Tap + to add your first.'),