feat(market): search + pull-to-refresh in the market list

Match the inventory patterns the market was missing:
- Search: OffersState gains a `query` + `visibleOffers` getter and
  OffersCubit.search() filters the already-discovered offers locally by
  summary (case-insensitive), never re-hitting the transport. The filter
  survives a refresh. Rounded search field mirrors inventory's.
- Pull-to-refresh: RefreshIndicator re-runs discovery for the current
  area (empty state included, so a swipe re-scans). Text filter kept.
- i18n: market.searchHint / market.noMatches (en/es/pt).

Note: the shared slang output (strings*.g.dart, incl. the generated
Asturian locale) is regenerated wholesale, so it also carries the
in-progress `ast` locale keys already present in the working tree.

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

@@ -219,6 +219,9 @@ class Translations$settings$en {
 	/// en: 'Português'
 	String get langPt => 'Português';
 
+	/// en: 'Asturianu'
+	String get langAst => 'Asturianu';
+
 	/// en: 'About'
 	String get about => 'About';
 
@@ -1101,6 +1104,12 @@ class Translations$market$en {
 	/// en: 'No seeds shared near you yet'
 	String get empty => 'No seeds shared near you yet';
 
+	/// en: 'Search these seeds'
+	String get searchHint => 'Search these seeds';
+
+	/// en: 'No shared seeds match your search'
+	String get noMatches => 'No shared seeds match your search';
+
 	/// en: 'Near you'
 	String get near => 'Near you';
 
@@ -1778,6 +1787,7 @@ extension on Translations {
 			'settings.langEs' => 'Español',
 			'settings.langEn' => 'English',
 			'settings.langPt' => 'Português',
+			'settings.langAst' => 'Asturianu',
 			'settings.about' => 'About',
 			'settings.aboutText' => 'Local-first, encrypted inventory for traditional seeds. AGPL-3.0.',
 			'settings.aboutOpen' => 'About Tanemaki',
@@ -2056,6 +2066,8 @@ extension on Translations {
 			'market.setAreaBody' => 'Tell the market roughly where you are to see seeds nearby.',
 			'market.searching' => 'Looking around your area…',
 			'market.empty' => 'No seeds shared near you yet',
+			'market.searchHint' => 'Search these seeds',
+			'market.noMatches' => 'No shared seeds match your search',
 			'market.near' => 'Near you',
 			'market.contact' => 'Message',
 			'market.mine' => 'You',