feat(inventory): month/year harvest date picker (schema v3)

Replace the free-text harvest year with a themed month/year picker:
a tappable field opens a green-styled dialog with month and year grids
(navigable, paginated years), month optional. Lots now read e.g.
"September 2021" or just "Year 2021".

- schema v3: add nullable Lot.harvest_month (1..12) + migration + tests
- repo/cubit propagate harvestMonth; localized month names (en/es) via slang

apps/app_seeds/lib/state/variety_detail_cubit.dart

@@ -1,4 +1,5 @@
 import 'dart:async';
+import 'dart:typed_data';
 
 import 'package:commons_core/commons_core.dart';
 import 'package:equatable/equatable.dart';
@@ -54,11 +55,13 @@ class VarietyDetailCubit extends Cubit<VarietyDetailState> {
   Future<void> addLot({
     LotType type = LotType.seed,
     int? year,
+    int? month,
     Quantity? quantity,
   }) => _repo.addLot(
     varietyId: varietyId,
     type: type,
     harvestYear: year,
+    harvestMonth: month,
     quantity: quantity,
   );
 
@@ -66,11 +69,13 @@ class VarietyDetailCubit extends Cubit<VarietyDetailState> {
     required String lotId,
     required LotType type,
     int? year,
+    int? month,
     Quantity? quantity,
   }) => _repo.updateLot(
     lotId: lotId,
     type: type,
     harvestYear: year,
+    harvestMonth: month,
     quantity: quantity,
   );
 
@@ -82,6 +87,11 @@ class VarietyDetailCubit extends Cubit<VarietyDetailState> {
   Future<void> removeVernacularName(String nameId) =>
       _repo.removeVernacularName(nameId);
 
+  Future<void> addPhoto(Uint8List bytes) => _repo.addPhoto(varietyId, bytes);
+
+  Future<void> removePhoto(String attachmentId) =>
+      _repo.removePhoto(attachmentId);
+
   Future<void> linkSpecies(String speciesId) =>
       _repo.linkSpecies(varietyId, speciesId);