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/ui/intro_screen_test.dart

@@ -0,0 +1,83 @@
+import 'package:flutter/material.dart';
+import 'package:flutter_test/flutter_test.dart';
+import 'package:tane/app.dart';
+import 'package:tane/i18n/strings.g.dart';
+import 'package:tane/ui/intro_screen.dart';
+
+import '../support/test_support.dart';
+
+void main() {
+  Widget standalone(VoidCallback onDone) => TranslationProvider(
+    child: MaterialApp(home: IntroScreen(onDone: onDone)),
+  );
+
+  testWidgets('carousel advances through slides and finishes', (tester) async {
+    LocaleSettings.setLocaleSync(AppLocale.en);
+    var done = false;
+
+    await tester.pumpWidget(standalone(() => done = true));
+    await tester.pumpAndSettle();
+
+    // First slide + a "Next" button (not "Get started" yet).
+    expect(find.text('The seed that brought you here'), findsOneWidget);
+    expect(find.text('Next'), findsOneWidget);
+    expect(find.text('Get started'), findsNothing);
+
+    // Advance to the last of the five slides.
+    for (var i = 0; i < 4; i++) {
+      await tester.tap(find.text('Next'));
+      await tester.pumpAndSettle();
+    }
+
+    expect(find.text('To sow is to multiply'), findsOneWidget);
+    expect(find.text('Get started'), findsOneWidget);
+
+    await tester.tap(find.text('Get started'));
+    await tester.pumpAndSettle();
+    expect(done, isTrue);
+  });
+
+  testWidgets('Skip finishes immediately', (tester) async {
+    LocaleSettings.setLocaleSync(AppLocale.en);
+    var done = false;
+
+    await tester.pumpWidget(standalone(() => done = true));
+    await tester.pumpAndSettle();
+
+    await tester.tap(find.text('Skip'));
+    await tester.pumpAndSettle();
+    expect(done, isTrue);
+  });
+
+  testWidgets('first launch opens on the intro and marks it seen', (
+    tester,
+  ) async {
+    LocaleSettings.setLocaleSync(AppLocale.en);
+    final db = newTestDatabase();
+    addTearDown(db.close);
+    final onboarding = newTestOnboardingStore(introSeen: false);
+
+    await tester.pumpWidget(
+      TranslationProvider(
+        child: TaneApp(
+          repository: newTestRepository(db),
+          species: newTestSpeciesRepository(db),
+          onboarding: onboarding,
+          showIntro: true,
+        ),
+      ),
+    );
+    await tester.pumpAndSettle();
+
+    // The carousel is shown, not the home menu.
+    expect(find.text('The seed that brought you here'), findsOneWidget);
+
+    await tester.tap(find.text('Skip'));
+    await tester.pumpAndSettle();
+
+    // Lands on home, and the intro is now remembered as seen.
+    expect(find.text('Your inventory'), findsOneWidget);
+    expect(await onboarding.introSeen(), isTrue);
+    await disposeTree(tester);
+  });
+}