feat(inventory): photo gallery + reactive avatars (+ harvest month/year)

Photos:
- Repository addPhoto/removePhoto; VarietyDetail.photos (list); loads all photos.
- Detail: a 140×140 photo carousel with page dots, delete-current, and add-photo
  (gallery); empty state shows an add-photo button.
- watchInventory now re-emits on attachment + species changes (StreamGroup), so
  a photo added on the detail screen refreshes the inventory avatar immediately
  (fixes avatars not updating).

Also carries the concurrent harvest-date work: lots gain an optional harvest
month (schemaVersion 3 + from2To3 migration, drift_schema_v3 exported), a
month/year harvest picker, and localized month names.

48 tests green (add/remove photos, avatar reactivity, v1→v3 migration); Linux runs.

apps/app_seeds/lib/data/variety_repository.dart

@@ -186,32 +186,45 @@ class VarietyRepository {
 
   /// Emits the non-deleted inventory, ordered by category then label, each with
   /// its first photo for the avatar.
+  ///
+  /// Re-emits on any change to varieties, their photos (attachments) or the
+  /// species catalog, so avatars and scientific names refresh reactively — a
+  /// photo added on the detail screen shows up in the list right away.
   Stream<List<VarietyListItem>> watchInventory() {
-    final query = _db.select(_db.varieties)
-      ..where((v) => v.isDeleted.equals(false))
-      ..orderBy([
-        (v) => OrderingTerm(expression: v.category),
-        (v) => OrderingTerm(expression: v.label),
-      ]);
-    return query.watch().asyncMap((rows) async {
-      final photos = await _firstPhotosFor(rows.map((v) => v.id).toList());
-      final sciNames = await _scientificNamesFor(
-        rows.map((v) => v.speciesId).whereType<String>().toSet(),
-      );
-      return rows
-          .map(
-            (v) => VarietyListItem(
-              id: v.id,
-              label: v.label,
-              category: v.category,
-              scientificName: v.speciesId == null
-                  ? null
-                  : sciNames[v.speciesId],
-              photo: photos[v.id],
-            ),
-          )
-          .toList();
-    });
+    final triggers = StreamGroup.merge<void>([
+      (_db.select(
+        _db.varieties,
+      )..where((v) => v.isDeleted.equals(false))).watch().map((_) {}),
+      _db.select(_db.attachments).watch().map((_) {}),
+      _db.select(_db.species).watch().map((_) {}),
+    ]);
+    return triggers.asyncMap((_) => _loadInventory());
+  }
+
+  Future<List<VarietyListItem>> _loadInventory() async {
+    final rows =
+        await (_db.select(_db.varieties)
+              ..where((v) => v.isDeleted.equals(false))
+              ..orderBy([
+                (v) => OrderingTerm(expression: v.category),
+                (v) => OrderingTerm(expression: v.label),
+              ]))
+            .get();
+    final photos = await _firstPhotosFor(rows.map((v) => v.id).toList());
+    final sciNames = await _scientificNamesFor(
+      rows.map((v) => v.speciesId).whereType<String>().toSet(),
+    );
+    return rows
+        .map(
+          (v) => VarietyListItem(
+            id: v.id,
+            label: v.label,
+            category: v.category,
+            scientificName: v.speciesId == null ? null : sciNames[v.speciesId],
+            photo: photos[v.id],
+          ),
+        )
+        .toList();
   }
 
   /// Loads the first photo BLOB for each of [varietyIds] (one query).

apps/app_seeds/test/data/variety_detail_test.dart

@@ -1,3 +1,5 @@
+import 'dart:typed_data';
+
 import 'package:async/async.dart';
 import 'package:commons_core/commons_core.dart';
 import 'package:flutter_test/flutter_test.dart';
@@ -184,4 +186,30 @@ void main() {
     await repo.removeVernacularName(nameId);
     expect((await repo.watchVariety(id).first)!.vernacularNames, isEmpty);
   });
+
+  test('add and remove photos (multiple, ordered)', () async {
+    final id = await repo.addQuickVariety(label: 'Maize');
+    final p1 = await repo.addPhoto(id, Uint8List.fromList([1, 2, 3]));
+    await repo.addPhoto(id, Uint8List.fromList([4, 5, 6]));
+
+    expect((await repo.watchVariety(id).first)!.photos.length, 2);
+
+    await repo.removePhoto(p1);
+    final photos = (await repo.watchVariety(id).first)!.photos;
+    expect(photos.map((p) => p.bytes.toList()), [
+      [4, 5, 6],
+    ]);
+  });
+
+  test('watchInventory avatar refreshes when a photo is added later', () async {
+    final id = await repo.addQuickVariety(label: 'Maize');
+    final queue = StreamQueue(repo.watchInventory());
+
+    expect((await queue.next).single.photo, isNull);
+
+    await repo.addPhoto(id, Uint8List.fromList([1, 2, 3]));
+    expect((await queue.next).single.photo, isNotNull);
+
+    await queue.cancel();
+  });
 }

apps/app_seeds/test/db/migration_test.dart

@@ -18,16 +18,13 @@ void main() {
     await db.close();
   });
 
-  test(
-    'upgrades v1 → v3 (adds Lot.type, then harvestMonth) and matches the '
-    'fresh schema',
-    () async {
-      final connection = await verifier.startAt(1);
-      final db = AppDatabase(connection);
-      await verifier.migrateAndValidate(db, 3);
-      await db.close();
-    },
-  );
+  test('upgrades v1 → v3 (adds Lot.type, then harvestMonth) and matches the '
+      'fresh schema', () async {
+    final connection = await verifier.startAt(1);
+    final db = AppDatabase(connection);
+    await verifier.migrateAndValidate(db, 3);
+    await db.close();
+  });
 
   test(
     'upgrades v2 → v3 (adds Lot.harvestMonth) and matches the fresh schema',