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/data/draft_capture_test.dart

@@ -0,0 +1,57 @@
+import 'dart:typed_data';
+
+import 'package:flutter_test/flutter_test.dart';
+import 'package:tane/data/variety_repository.dart';
+import 'package:tane/db/database.dart';
+
+import '../support/test_support.dart';
+
+void main() {
+  late AppDatabase db;
+  late VarietyRepository repo;
+
+  setUp(() {
+    db = newTestDatabase();
+    repo = newTestRepository(db);
+  });
+  tearDown(() => db.close());
+
+  Uint8List photo(int seed) => Uint8List.fromList([seed, seed, seed]);
+
+  test('a captured draft is hidden from the list but shown in the tray',
+      () async {
+    final id = await repo.addDraftVariety(photo(1));
+
+    // Not in the main inventory…
+    expect(await repo.watchInventory().first, isEmpty);
+
+    // …but in the "to catalogue" tray, with its photo and no name yet.
+    final drafts = await repo.watchDrafts().first;
+    expect(drafts, hasLength(1));
+    expect(drafts.single.id, id);
+    expect(drafts.single.isDraft, isTrue);
+    expect(drafts.single.label, '');
+    expect(drafts.single.photo, isNotNull);
+  });
+
+  test('naming a draft promotes it into the list and out of the tray',
+      () async {
+    final id = await repo.addDraftVariety(photo(2));
+    await repo.nameDraft(id, 'Grandma tomato');
+
+    expect(await repo.watchDrafts().first, isEmpty);
+    final list = await repo.watchInventory().first;
+    expect(list.single.id, id);
+    expect(list.single.label, 'Grandma tomato');
+    expect(list.single.isDraft, isFalse);
+    // The captured photo survived the promotion.
+    expect(list.single.photo, isNotNull);
+  });
+
+  test('the tray is ordered newest-capture first', () async {
+    final first = await repo.addDraftVariety(photo(1));
+    final second = await repo.addDraftVariety(photo(2));
+    final drafts = await repo.watchDrafts().first;
+    expect(drafts.map((d) => d.id).toList(), [second, first]);
+  });
+}