feat(block2): publish my seeds to the network (completes publish->discover)

The other half of the market: share your marked lots as offers.
- VarietyRepository.shareableLots(): non-private lots WITH their id (stable,
  updatable offer id) + the variety label. Private lots never leave the device.
- OffersCubit.publishLots(): maps each via OfferMapper and publishes, tagged
  with the coarse area + signed by the derived key; counts acceptances; no-op
  offline or with no area.
- Market screen: a 'share my seeds' action (online only) — publishes, then
  re-discovers to show them; 'mark some seeds first' when nothing's shared.
- i18n en/es/pt.

14 tests green (repo query, cubit publish, market UI); analyzer clean for new code.

apps/app_seeds/lib/i18n/en.i18n.json

@@ -348,6 +348,9 @@
     "serversLabel": "Web address",
     "save": "Save",
     "saved": "Saved",
-    "wanted": "Wanted"
+    "wanted": "Wanted",
+    "shareMine": "Share my seeds",
+    "sharedCount": "Shared {n} seeds nearby",
+    "nothingToShare": "Mark some seeds to give, swap or sell first"
   }
 }

apps/app_seeds/lib/i18n/es.i18n.json

@@ -348,6 +348,9 @@
     "serversLabel": "Dirección web",
     "save": "Guardar",
     "saved": "Guardado",
-    "wanted": "Busco"
+    "wanted": "Busco",
+    "shareMine": "Compartir mis semillas",
+    "sharedCount": "Compartidas {n} semillas",
+    "nothingToShare": "Marca antes algunas semillas para regalar, cambiar o vender"
   }
 }

apps/app_seeds/lib/i18n/pt.i18n.json

@@ -344,6 +344,9 @@
     "serversLabel": "Endereço web",
     "save": "Guardar",
     "saved": "Guardado",
-    "wanted": "Procuro"
+    "wanted": "Procuro",
+    "shareMine": "Partilhar as minhas sementes",
+    "sharedCount": "Partilhadas {n} sementes",
+    "nothingToShare": "Marca primeiro algumas sementes para dar, trocar ou vender"
   }
 }

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

@@ -4,9 +4,9 @@
 /// To regenerate, run: `dart run slang`
 ///
 /// Locales: 3
-/// Strings: 929 (309 per locale)
+/// Strings: 938 (312 per locale)
 ///
-/// Built on 2026-07-10 at 01:15 UTC
+/// Built on 2026-07-10 at 08:17 UTC
 
 // coverage:ignore-file
 // ignore_for_file: type=lint, unused_import

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

@@ -1105,6 +1105,15 @@ class Translations$market$en {
 
 	/// en: 'Wanted'
 	String get wanted => 'Wanted';
+
+	/// en: 'Share my seeds'
+	String get shareMine => 'Share my seeds';
+
+	/// en: 'Shared {n} seeds nearby'
+	String sharedCount({required Object n}) => 'Shared ${n} seeds nearby';
+
+	/// en: 'Mark some seeds to give, swap or sell first'
+	String get nothingToShare => 'Mark some seeds to give, swap or sell first';
 }
 
 // Path: intro.slides
@@ -1875,6 +1884,9 @@ extension on Translations {
 			'market.save' => 'Save',
 			'market.saved' => 'Saved',
 			'market.wanted' => 'Wanted',
+			'market.shareMine' => 'Share my seeds',
+			'market.sharedCount' => ({required Object n}) => 'Shared ${n} seeds nearby',
+			'market.nothingToShare' => 'Mark some seeds to give, swap or sell first',
 			_ => null,
 		};
 	}

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

@@ -619,6 +619,9 @@ class _Translations$market$es extends Translations$market$en {
 	@override String get save => 'Guardar';
 	@override String get saved => 'Guardado';
 	@override String get wanted => 'Busco';
+	@override String get shareMine => 'Compartir mis semillas';
+	@override String sharedCount({required Object n}) => 'Compartidas ${n} semillas';
+	@override String get nothingToShare => 'Marca antes algunas semillas para regalar, cambiar o vender';
 }
 
 // Path: intro.slides
@@ -1273,6 +1276,9 @@ extension on TranslationsEs {
 			'market.save' => 'Guardar',
 			'market.saved' => 'Guardado',
 			'market.wanted' => 'Busco',
+			'market.shareMine' => 'Compartir mis semillas',
+			'market.sharedCount' => ({required Object n}) => 'Compartidas ${n} semillas',
+			'market.nothingToShare' => 'Marca antes algunas semillas para regalar, cambiar o vender',
 			_ => null,
 		};
 	}

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

@@ -615,6 +615,9 @@ class _Translations$market$pt extends Translations$market$en {
 	@override String get save => 'Guardar';
 	@override String get saved => 'Guardado';
 	@override String get wanted => 'Procuro';
+	@override String get shareMine => 'Partilhar as minhas sementes';
+	@override String sharedCount({required Object n}) => 'Partilhadas ${n} sementes';
+	@override String get nothingToShare => 'Marca primeiro algumas sementes para dar, trocar ou vender';
 }
 
 // Path: intro.slides
@@ -1265,6 +1268,9 @@ extension on TranslationsPt {
 			'market.save' => 'Guardar',
 			'market.saved' => 'Guardado',
 			'market.wanted' => 'Procuro',
+			'market.shareMine' => 'Partilhar as minhas sementes',
+			'market.sharedCount' => ({required Object n}) => 'Partilhadas ${n} sementes',
+			'market.nothingToShare' => 'Marca primeiro algumas sementes para dar, trocar ou vender',
 			_ => null,
 		};
 	}