feat(species): auto-classify variety species from its label

Infer the catalog species a free-text variety label names ("Maiz de la
abuela" -> Zea mays) and prefill the category from the species family.

- Pure, testable matcher (domain/species_autoclassify.dart): whole-word,
  accent/case-insensitive, Unicode-aware (any script), longest-name-wins,
  ambiguous names left unclassified, light plural fold.
- Quick-add and draft naming auto-link the species when the field is empty
  (non-destructive; an explicit category is kept).
- Edit sheet offers a one-tap suggestion from the typed name.

Tests: matcher unit, repository integration, SpeciesRepository.classifyLabel,
and an edit-sheet widget test.

apps/app_seeds/lib/ui/variety_detail_screen.dart

@@ -605,6 +605,11 @@ class _EditVarietySheetState extends State<_EditVarietySheet> {
 
   List<SpeciesMatch> _suggestions = const [];
   String? _pickedSpeciesId;
+
+  /// A species inferred from the typed name, offered as a one-tap suggestion.
+  /// Only surfaced while the variety has no species and the grower has not
+  /// picked one, so it never nags over a deliberate choice.
+  SpeciesMatch? _suggested;
   late bool _isOrganic = widget.detail.isOrganic;
   late bool _needsReproduction = widget.detail.needsReproduction;
   late int? _sowMonths = widget.detail.sowMonths;
@@ -626,14 +631,26 @@ class _EditVarietySheetState extends State<_EditVarietySheet> {
   Future<void> _onSpeciesQuery(String query) async {
     final lang = Localizations.localeOf(context).languageCode;
     final results = await widget.species.search(query, languageCode: lang);
+    // A manual species search takes over from the name-based suggestion.
     if (mounted) setState(() => _suggestions = results);
   }
 
+  /// As the name is typed, offer the species it names — but only when the
+  /// variety has no species yet and the grower hasn't picked one, so an
+  /// existing link is never second-guessed.
+  Future<void> _onNameChanged(String name) async {
+    if (widget.detail.speciesId != null || _pickedSpeciesId != null) return;
+    final lang = Localizations.localeOf(context).languageCode;
+    final match = await widget.species.classifyLabel(name, languageCode: lang);
+    if (mounted) setState(() => _suggested = match);
+  }
+
   void _pick(SpeciesMatch match) {
     setState(() {
       _pickedSpeciesId = match.id;
       _speciesField.text = match.displayLabel;
       _suggestions = const [];
+      _suggested = null;
     });
   }
 
@@ -694,6 +711,7 @@ class _EditVarietySheetState extends State<_EditVarietySheet> {
                         borderRadius: BorderRadius.all(Radius.circular(8)),
                       ),
                     ),
+                    onChanged: _onNameChanged,
                   ),
                   const SizedBox(height: 12),
                   TextField(
@@ -719,6 +737,19 @@ class _EditVarietySheetState extends State<_EditVarietySheet> {
                           : Text(match.family!),
                       onTap: () => _pick(match),
                     ),
+                  // One-tap suggestion inferred from the name (only when the
+                  // species field is idle, so it never competes with a manual
+                  // search).
+                  if (_suggested case final suggested?
+                      when _suggestions.isEmpty && _pickedSpeciesId == null)
+                    ListTile(
+                      dense: true,
+                      key: const Key('editVariety.speciesSuggestion'),
+                      leading: const Icon(Icons.auto_awesome_outlined),
+                      title: Text(suggested.displayLabel),
+                      subtitle: Text(t.editVariety.speciesSuggested),
+                      onTap: () => _pick(suggested),
+                    ),
                   const SizedBox(height: 12),
                   TextField(
                     controller: _category,