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/domain/crop_calendar_test.dart

@@ -0,0 +1,45 @@
+import 'package:flutter_test/flutter_test.dart';
+import 'package:tane/domain/crop_calendar.dart';
+
+void main() {
+  test('an empty month set packs to null, not 0', () {
+    expect(monthsToMask(const []), isNull);
+    expect(monthsToMask(const [0, 13, -1]), isNull); // out of range ignored
+  });
+
+  test('months round-trip through the mask, ascending and deduped', () {
+    final mask = monthsToMask(const [9, 3, 4, 3]);
+    expect(maskToMonths(mask), [3, 4, 9]);
+  });
+
+  test('every single month packs to a distinct bit', () {
+    for (var m = 1; m <= 12; m++) {
+      expect(maskToMonths(monthsToMask([m])), [m]);
+    }
+  });
+
+  test('maskToMonths of null or 0 is empty', () {
+    expect(maskToMonths(null), isEmpty);
+    expect(maskToMonths(0), isEmpty);
+  });
+
+  test('maskHasMonth reflects set bits', () {
+    final mask = monthsToMask(const [3, 9]);
+    expect(maskHasMonth(mask, 3), isTrue);
+    expect(maskHasMonth(mask, 9), isTrue);
+    expect(maskHasMonth(mask, 4), isFalse);
+    expect(maskHasMonth(null, 3), isFalse);
+    expect(maskHasMonth(mask, 0), isFalse);
+  });
+
+  test('toggleMonth adds, removes, and clears to null when empty', () {
+    var mask = toggleMonth(null, 3);
+    expect(maskToMonths(mask), [3]);
+    mask = toggleMonth(mask, 9);
+    expect(maskToMonths(mask), [3, 9]);
+    mask = toggleMonth(mask, 3);
+    expect(maskToMonths(mask), [9]);
+    mask = toggleMonth(mask, 9);
+    expect(mask, isNull); // last month removed → null, not 0
+  });
+}