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.g.dart

@@ -3,10 +3,10 @@
 /// Source: lib/i18n
 /// To regenerate, run: `dart run slang`
 ///
-/// Locales: 3
-/// Strings: 1073 (357 per locale)
+/// Locales: 4
+/// Strings: 1441 (360 per locale)
 ///
-/// Built on 2026-07-10 at 11:35 UTC
+/// Built on 2026-07-10 at 13:39 UTC
 
 // coverage:ignore-file
 // ignore_for_file: type=lint, unused_import
@@ -18,6 +18,7 @@ import 'package:slang/generated.dart';
 import 'package:slang_flutter/slang_flutter.dart';
 export 'package:slang_flutter/slang_flutter.dart';
 
+import 'strings_ast.g.dart' as l_ast;
 import 'strings_es.g.dart' as l_es;
 import 'strings_pt.g.dart' as l_pt;
 part 'strings_en.g.dart';
@@ -30,6 +31,7 @@ part 'strings_en.g.dart';
 /// - if (LocaleSettings.currentLocale == AppLocale.en) // locale check
 enum AppLocale with BaseAppLocale<AppLocale, Translations> {
 	en(languageCode: 'en'),
+	ast(languageCode: 'ast'),
 	es(languageCode: 'es'),
 	pt(languageCode: 'pt');
 
@@ -69,6 +71,12 @@ enum AppLocale with BaseAppLocale<AppLocale, Translations> {
 					cardinalResolver: cardinalResolver,
 					ordinalResolver: ordinalResolver,
 				);
+			case AppLocale.ast:
+				return l_ast.TranslationsAst(
+					overrides: overrides,
+					cardinalResolver: cardinalResolver,
+					ordinalResolver: ordinalResolver,
+				);
 			case AppLocale.es:
 				return l_es.TranslationsEs(
 					overrides: overrides,