feat(market): fix publish-duplicates, add offer detail page + filters

The vecino/market view had three gaps:

- Publishing inventory duplicated the listing. discover() appended every
  offer the relay streamed, but relays legitimately resend an addressable
  NIP-99 event (stored copy + live echo on publish). Merge by
  (authorPubkeyHex, id) so each offer appears once; two authors reusing a
  lot id stay distinct.
- No product detail. Tapping a card jumped straight to chat. Add a
  read-only "product page" (MarketOfferDetailScreen) with title, mode,
  category, eco badge, coarse location, price, a "Shared by" seller
  section (profile fetched by pubkey) and the message button. Reached via
  a new /market/offer route; cards are now fully tappable. Shows only what
  the network already carries — no photos/description added to the wire.
- No filters. Add a filter bar (type, category, eco) mirroring inventory,
  each chip group shown only when a discovered offer can match it. To make
  the eco filter real, publish the organic flag on the wire: Offer.isOrganic
  -> NIP-99 'organic' tag -> OfferMapper -> ShareableLot.

Tests: commons_core organic round-trip; app-side dedup, two-author
separation, filter logic, mapper passthrough; detail-screen widget tests.
i18n keys added to en/es/pt/ast and slang regenerated.

apps/app_seeds/lib/services/offer_mapper.dart

@@ -29,6 +29,7 @@ class OfferMapper {
     required OfferStatus sharing,
     required String areaGeohash,
     String? category,
+    bool isOrganic = false,
     num? priceAmount,
     String? priceCurrency,
     String? exchangeTerms,
@@ -43,6 +44,7 @@ class OfferMapper {
       type: type,
       approxGeohash: areaGeohash,
       category: category,
+      isOrganic: isOrganic,
       priceAmount: type == OfferType.sale ? priceAmount : null,
       priceCurrency: type == OfferType.sale ? priceCurrency : null,
       exchangeTerms: type == OfferType.exchange ? exchangeTerms : null,