feat(inventory): photo-first drafts + on-device OCR (digitization R2+R4)

Lower the bulk-digitization cliff with two more routes on top of the
already-landed CSV import and "save and add another":

- Photo-first drafts (capture now, catalogue later): burst-capture
  photos (camera or multi-gallery) into unnamed draft varieties, shown
  in a "to catalogue" tray, hidden from the main list until named.
  Adds Variety.isDraft (schema), addDraftVariety/watchDrafts/nameDraft,
  the triage sheet and the inventory banner.
- On-device OCR label suggestion (Tesseract, offline, no Google): a
  "Suggest name from photo" button in the naming dialog behind a
  LabelTextExtractor interface (Tesseract on Android/iOS, no-op
  elsewhere). Reads the largest print via hOCR bounding boxes, drops
  boilerplate/low-confidence noise, preprocesses (grayscale, contrast,
  upscale) and sweeps rotations (0-315 deg) so tilted packets still
  read. Bundles tessdata_fast eng+spa; validated on-device against real
  packets. The photo is written to a temp file deleted immediately in a
  finally block (the plugin needs a path) - a bounded, documented
  exception to no-plaintext-at-rest.

This commit also carries the co-developed schema evolution v5 to v8 that
shares these files (organic flag, species viability years, crop
calendar, lot provenance/abundance/preservation format, condition
checks) plus their exports/migrations and i18n.

Tests: CSV/draft/OCR unit + widget + migration green in isolation.
Note: the full widget suite currently hangs (>10 min) - under investigation.

apps/app_seeds/test/support/test_support.dart

@@ -8,6 +8,8 @@ import 'package:tane/data/species_repository.dart';
 import 'package:tane/data/variety_repository.dart';
 import 'package:tane/db/database.dart';
 import 'package:tane/i18n/strings.g.dart';
+import 'package:tane/security/secret_store.dart';
+import 'package:tane/services/onboarding_store.dart';
 import 'package:tane/state/inventory_cubit.dart';
 import 'package:tane/state/variety_detail_cubit.dart';
 import 'package:tane/ui/variety_detail_screen.dart';
@@ -33,6 +35,25 @@ VarietyRepository newTestRepository(
 SpeciesRepository newTestSpeciesRepository(AppDatabase db) =>
     SpeciesRepository(db, idGen: IdGen());
 
+/// An in-memory [SecretStore] for tests (no OS keystore).
+class InMemorySecretStore implements SecretStore {
+  final Map<String, String> _values = {};
+
+  @override
+  Future<String?> read(String key) async => _values[key];
+
+  @override
+  Future<void> write(String key, String value) async => _values[key] = value;
+}
+
+/// A fresh [OnboardingStore] backed by in-memory storage. Defaults to
+/// "intro already seen" so app-level tests land on home, not the carousel.
+OnboardingStore newTestOnboardingStore({bool introSeen = true}) {
+  final store = InMemorySecretStore();
+  if (introSeen) store.write('tane.intro_seen', '1');
+  return OnboardingStore(store);
+}
+
 /// Wraps [child] with the providers a screen expects (repository, inventory
 /// cubit) plus i18n and Material localizations, pinned to [locale].
 Widget wrapScreen({