feat(species): derived verified reference links (GBIF/Wikipedia/Wikispecies)

Add a read-only "Learn more" section on the variety detail that surfaces
verified external references for the linked species, built deterministically
from bundled identifiers — no titles bundled, no network, offline-first:

- GBIF taxon page from the backbone key
- Wikipedia via Wikidata Special:GoToLinkedPage (locale-aware, RTL-safe,
  falls back to the Wikidata item when a language lacks the article)
- Wikispecies from the scientific name

Enrich the bundled catalog (species.json v3) with gbif_key + wikidata_qid for
all 14 species, cross-checked (each QID carries GBIF ID P846 = the key).
Schema already had the columns; seedBundled now persists and backfills them.

The grower's own manual links stay but are demoted (progressive disclosure):
the section only shows when links exist and "Add link" is a low-emphasis
button, since hand-adding a link is the rarer power move.

Pure-Dart link builder is unit-tested; repo persistence/backfill and the
detail-screen section are covered too.

apps/app_seeds/lib/i18n/strings_en.g.dart

@@ -495,6 +495,18 @@ class Translations$detail$en {
 	/// en: 'Title (optional)'
 	String get linkTitle => 'Title (optional)';
 
+	/// en: 'Learn more'
+	String get reference => 'Learn more';
+
+	/// en: 'GBIF'
+	String get refGbif => 'GBIF';
+
+	/// en: 'Wikipedia'
+	String get refWikipedia => 'Wikipedia';
+
+	/// en: 'Wikispecies'
+	String get refWikispecies => 'Wikispecies';
+
 	/// en: 'Notes'
 	String get notes => 'Notes';
 
@@ -1564,6 +1576,10 @@ extension on Translations {
 			'detail.addLink' => 'Add link',
 			'detail.linkUrl' => 'URL',
 			'detail.linkTitle' => 'Title (optional)',
+			'detail.reference' => 'Learn more',
+			'detail.refGbif' => 'GBIF',
+			'detail.refWikipedia' => 'Wikipedia',
+			'detail.refWikispecies' => 'Wikispecies',
 			'detail.notes' => 'Notes',
 			'detail.addLot' => 'Add lot',
 			'detail.editLot' => 'Edit lot',