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/lib/db/database.dart

@@ -17,6 +17,7 @@ part 'database.g.dart';
     SpeciesCommonNames,
     Lots,
     GerminationTests,
+    ConditionChecks,
     Movements,
     Parties,
     Attachments,
@@ -28,7 +29,7 @@ class AppDatabase extends _$AppDatabase {
 
   /// Current schema version; also stamped into interchange exports so an
   /// importer knows which app generation wrote the file (data-model §7).
-  static const int currentSchemaVersion = 5;
+  static const int currentSchemaVersion = 8;
 
   @override
   int get schemaVersion => currentSchemaVersion;
@@ -53,6 +54,110 @@ class AppDatabase extends _$AppDatabase {
       if (from < 5) {
         await m.addColumn(attachments, attachments.sortOrder);
       }
+      // v6: photo-first draft varieties awaiting a name ("to catalogue" tray).
+      if (from < 6) {
+        await m.addColumn(varieties, varieties.isDraft);
+      }
+      // v7: organic ("eco") self-declaration on varieties; per-species seed
+      // viability (years) reference data for expiry warnings. Guarded by a
+      // column-existence check so a dev database left half-migrated (column
+      // added but user_version not bumped) re-runs cleanly instead of failing
+      // on "duplicate column".
+      if (from < 7) {
+        if (!await _hasColumn('varieties', 'is_organic')) {
+          await m.addColumn(varieties, varieties.isOrganic);
+        }
+        if (!await _hasColumn('species', 'viability_years')) {
+          await m.addColumn(species, species.viabilityYears);
+        }
+      }
+      // v8: absorbs fields from a real seed-bank inventory. Varieties gain a
+      // "needs reproducing" intent and an advisory crop calendar; Lots gain
+      // provenance (origin name/place), a qualitative abundance level and a
+      // preservation format; a new ConditionChecks table logs container count +
+      // drying-agent state. Every step is guarded so a half-migrated dev
+      // database re-runs cleanly (see the v7 note above).
+      if (from < 8) {
+        Future<void> addIfMissing(
+          String table,
+          String column,
+          GeneratedColumn<Object> definition,
+          TableInfo<Table, dynamic> tableInfo,
+        ) async {
+          if (!await _hasColumn(table, column)) {
+            await m.addColumn(tableInfo, definition);
+          }
+        }
+
+        await addIfMissing(
+          'varieties',
+          'needs_reproduction',
+          varieties.needsReproduction,
+          varieties,
+        );
+        await addIfMissing(
+          'varieties',
+          'sow_months',
+          varieties.sowMonths,
+          varieties,
+        );
+        await addIfMissing(
+          'varieties',
+          'transplant_months',
+          varieties.transplantMonths,
+          varieties,
+        );
+        await addIfMissing(
+          'varieties',
+          'flowering_months',
+          varieties.floweringMonths,
+          varieties,
+        );
+        await addIfMissing(
+          'varieties',
+          'fruiting_months',
+          varieties.fruitingMonths,
+          varieties,
+        );
+        await addIfMissing(
+          'varieties',
+          'seed_harvest_months',
+          varieties.seedHarvestMonths,
+          varieties,
+        );
+        await addIfMissing('lots', 'origin_name', lots.originName, lots);
+        await addIfMissing('lots', 'origin_place', lots.originPlace, lots);
+        await addIfMissing('lots', 'abundance', lots.abundance, lots);
+        await addIfMissing(
+          'lots',
+          'preservation_format',
+          lots.preservationFormat,
+          lots,
+        );
+        if (!await _hasTable('condition_checks')) {
+          await m.createTable(conditionChecks);
+        }
+      }
     },
   );
+
+  /// Whether a table named [table] already exists. Keeps the additive v8
+  /// table creation idempotent against partially-migrated databases.
+  Future<bool> _hasTable(String table) async {
+    final rows = await customSelect(
+      "SELECT 1 FROM sqlite_master WHERE type = 'table' AND name = ?",
+      variables: [Variable.withString(table)],
+    ).get();
+    return rows.isNotEmpty;
+  }
+
+  /// Whether [table] already has a column named [column]. Used to keep additive
+  /// migrations idempotent against partially-migrated databases.
+  Future<bool> _hasColumn(String table, String column) async {
+    final rows = await customSelect(
+      'SELECT 1 FROM pragma_table_info(?) WHERE name = ?',
+      variables: [Variable.withString(table), Variable.withString(column)],
+    ).get();
+    return rows.isNotEmpty;
+  }
 }