feat(block1): photo thumbnails in the inventory list

The list showed only initials even when a variety had a photo (quick-add stores
one as an encrypted BLOB). Now the avatar shows the first photo, falling back to
the initial — matching the "foto/inicial" list spec.

- VarietyListItem carries the first photo bytes; watchInventory loads them in a
  single query per emission.
- List tile renders a MemoryImage avatar when present.

Tests: repository (photo bytes surfaced, null when none) and a widget test
(avatar replaces the initial). Full suite: 37 passing, 0 skipped.

apps/app_seeds/lib/data/variety_repository.dart

@@ -8,14 +8,22 @@ import '../db/enums.dart';
 
 /// A lightweight row for the inventory list (only what the list renders).
 class VarietyListItem extends Equatable {
-  const VarietyListItem({required this.id, required this.label, this.category});
+  const VarietyListItem({
+    required this.id,
+    required this.label,
+    this.category,
+    this.photo,
+  });
 
   final String id;
   final String label;
   final String? category;
 
+  /// First photo (encrypted BLOB) for the avatar, or null → show an initial.
+  final Uint8List? photo;
+
   @override
-  List<Object?> get props => [id, label, category];
+  List<Object?> get props => [id, label, category, photo];
 }
 
 /// One germination test on a lot; [rate] is derived (0..1), null when it can't
@@ -135,7 +143,8 @@ class VarietyRepository {
   final int Function() _now;
   Hlc _clock;
 
-  /// Emits the non-deleted inventory, ordered by category then label.
+  /// Emits the non-deleted inventory, ordered by category then label, each with
+  /// its first photo for the avatar.
   Stream<List<VarietyListItem>> watchInventory() {
     final query = _db.select(_db.varieties)
       ..where((v) => v.isDeleted.equals(false))
@@ -143,14 +152,41 @@ class VarietyRepository {
         (v) => OrderingTerm(expression: v.category),
         (v) => OrderingTerm(expression: v.label),
       ]);
-    return query.watch().map(
-      (rows) => rows
+    return query.watch().asyncMap((rows) async {
+      final photos = await _firstPhotosFor(rows.map((v) => v.id).toList());
+      return rows
           .map(
-            (v) =>
-                VarietyListItem(id: v.id, label: v.label, category: v.category),
+            (v) => VarietyListItem(
+              id: v.id,
+              label: v.label,
+              category: v.category,
+              photo: photos[v.id],
+            ),
           )
-          .toList(),
-    );
+          .toList();
+    });
+  }
+
+  /// Loads the first photo BLOB for each of [varietyIds] (one query).
+  Future<Map<String, Uint8List>> _firstPhotosFor(
+    List<String> varietyIds,
+  ) async {
+    if (varietyIds.isEmpty) return const {};
+    final rows =
+        await (_db.select(_db.attachments)..where(
+              (a) =>
+                  a.parentId.isIn(varietyIds) &
+                  a.parentType.equalsValue(ParentType.variety) &
+                  a.kind.equalsValue(AttachmentKind.photo) &
+                  a.isDeleted.equals(false),
+            ))
+            .get();
+    final byVariety = <String, Uint8List>{};
+    for (final row in rows) {
+      final bytes = row.bytes;
+      if (bytes != null) byVariety.putIfAbsent(row.parentId, () => bytes);
+    }
+    return byVariety;
   }
 
   /// The 20-second quick-add: a [label] (required) plus an optional [category],

apps/app_seeds/lib/ui/inventory_list_screen.dart

@@ -122,7 +122,9 @@ class _VarietyTile extends StatelessWidget {
         ? '?'
         : trimmed.substring(0, 1).toUpperCase();
     return ListTile(
-      leading: CircleAvatar(child: Text(initial)),
+      leading: item.photo != null
+          ? CircleAvatar(backgroundImage: MemoryImage(item.photo!))
+          : CircleAvatar(child: Text(initial)),
       title: Text(item.label),
       onTap: () => context.push('/variety/${item.id}'),
     );

apps/app_seeds/test/data/variety_repository_test.dart

@@ -52,6 +52,18 @@ void main() {
     },
   );
 
+  test('watchInventory carries the first photo bytes for the avatar', () async {
+    await repo.addQuickVariety(
+      label: 'With photo',
+      photoBytes: Uint8List.fromList([9, 8, 7]),
+    );
+    await repo.addQuickVariety(label: 'No photo');
+
+    final items = await repo.watchInventory().first;
+    expect(items.firstWhere((i) => i.label == 'With photo').photo, [9, 8, 7]);
+    expect(items.firstWhere((i) => i.label == 'No photo').photo, isNull);
+  });
+
   test(
     'stream is ordered by category then label and excludes soft-deleted rows',
     () async {

apps/app_seeds/test/ui/inventory_list_screen_test.dart

@@ -1,3 +1,5 @@
+import 'dart:typed_data';
+
 import 'package:flutter/material.dart';
 import 'package:flutter_test/flutter_test.dart';
 import 'package:tane/db/database.dart';
@@ -6,6 +8,14 @@ import 'package:tane/ui/inventory_list_screen.dart';
 
 import '../support/test_support.dart';
 
+/// A valid 1x1 transparent PNG so the avatar image decodes cleanly in tests.
+final _tinyPng = Uint8List.fromList(const [
+  137, 80, 78, 71, 13, 10, 26, 10, 0, 0, 0, 13, 73, 72, 68, 82, 0, 0, 0, 1, //
+  0, 0, 0, 1, 8, 6, 0, 0, 0, 31, 21, 196, 137, 0, 0, 0, 13, 73, 68, 65, 84, //
+  120, 156, 99, 250, 207, 0, 0, 0, 2, 0, 1, 226, 33, 188, 51, 0, 0, 0, 0, //
+  73, 69, 78, 68, 174, 66, 96, 130,
+]);
+
 void main() {
   late AppDatabase db;
 
@@ -75,4 +85,21 @@ void main() {
     expect(find.text('Inventario'), findsOneWidget);
     await disposeTree(tester);
   });
+
+  testWidgets(
+    'shows a photo avatar instead of the initial when a photo exists',
+    (tester) async {
+      final repo = newTestRepository(db);
+      await repo.addQuickVariety(label: 'Photographed', photoBytes: _tinyPng);
+
+      await tester.pumpWidget(
+        wrapScreen(repository: repo, child: const InventoryListScreen()),
+      );
+      await tester.pumpAndSettle();
+
+      expect(find.text('Photographed'), findsOneWidget);
+      expect(find.text('P'), findsNothing); // initial replaced by the photo
+      await disposeTree(tester);
+    },
+  );
 }