feat(seed-saving): per-crop 'how to save this seed' guidance

A bundled, curated knowledge layer — the differentiator of a serious
seed app. For a variety's crop it shows how the plant reproduces and what
it takes to keep the variety true: life cycle, pollination (self/cross +
insect/wind), isolation distance, how many plants to save from, dry/wet
processing, a difficulty pill, and a short tip — all in human words.

- assets/catalog/seed_saving.json: curated public-domain data (Seed to
  Seed / Seed Savers), keyed by botanical FAMILY (defaults) with
  per-species/genus OVERRIDES that win — so e.g. Vicia faba is correctly
  insect-cross-pollinated despite the selfing Fabaceae default, and maize
  is wind-pollinated with a large population. Notes are locale-keyed
  (es/en), extensible to any language — a starter set, not a ceiling.
- domain/seed_saving.dart (pure): enums + SeedSavingGuide (merge, note
  fallback) + SeedSavingData.guideFor (species → genus → family).
- data/seed_saving_catalog.dart: loads the asset once into an in-memory
  singleton (no DB table, no migration); injector loads it at startup.
- VarietyDetail gains  (from the linked species — the reliable
  key, vs the editable category); detail screen shows a _SeedSavingView
  when a guide resolves.
- i18n seedSaving block (labels + enum values + params) in en/es/pt/ast.
- Tests: domain lookup/merge, the real asset's key corrections, and the
  detail section shows/hides. 314 suite tests green; analyze clean.

apps/app_seeds/lib/di/injector.dart

@@ -9,6 +9,7 @@ import 'package:get_it/get_it.dart';
 import 'package:path/path.dart' as p;
 import 'package:path_provider/path_provider.dart';
 
+import '../data/seed_saving_catalog.dart';
 import '../data/species_catalog.dart';
 import '../data/species_repository.dart';
 import '../data/variety_repository.dart';
@@ -141,6 +142,10 @@ Future<void> configureDependencies() async {
     loadSeeds: loadBundledSpecies,
   );
 
+  // Small read-only reference data — kept in memory, not the DB. Loaded before
+  // the UI so the variety detail can show seed-saving guidance synchronously.
+  await SeedSavingCatalog.ensureLoaded();
+
   final varietyRepository = VarietyRepository(
     database,
     idGen: IdGen(),