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/ui/market_widgets.dart

@@ -0,0 +1,41 @@
+import 'package:commons_core/commons_core.dart';
+import 'package:flutter/material.dart';
+
+import '../i18n/strings.g.dart';
+import 'theme.dart';
+
+/// Human words for an offer's reciprocity mode. Shared by the market list and
+/// the offer detail page so both read the same way.
+String offerTypeLabel(Translations t, OfferType type) => switch (type) {
+      OfferType.gift => t.share.gift,
+      OfferType.exchange => t.share.exchange,
+      OfferType.sale => t.share.sell,
+      OfferType.wanted => t.market.wanted,
+      OfferType.lend => t.share.exchange,
+    };
+
+/// The small pill showing an offer's reciprocity mode (give/swap/sell/wanted).
+class OfferTypeChip extends StatelessWidget {
+  const OfferTypeChip({required this.label, super.key});
+
+  final String label;
+
+  @override
+  Widget build(BuildContext context) {
+    return Container(
+      padding: const EdgeInsets.symmetric(horizontal: 10, vertical: 4),
+      decoration: BoxDecoration(
+        color: seedPrimaryContainer,
+        borderRadius: BorderRadius.circular(20),
+      ),
+      child: Text(
+        label,
+        style: const TextStyle(
+          color: seedOnPrimaryContainer,
+          fontSize: 12,
+          fontWeight: FontWeight.w600,
+        ),
+      ),
+    );
+  }
+}