feat(block2): market screen — discover seeds near you (offers UI)

Wires the 'coming soon' market card to a real discovery screen (mockups 04/05):
- MarketScreen: opens an OfferTransport lazily; local-first, so it degrades to a
  human 'set up sharing' prompt when no relay/area is set or the net is down.
- Discovers offers by the saved coarse area, lists them with human reciprocity
  labels (gift/swap/for sale), 'near you' (never exact location), price only for
  sales. Config sheet to set area + community servers (no bundled public relays).
- Threaded via TaneApp(social, socialSettings) — null keeps the card 'coming
  soon' (so Block 1 tests pass unchanged); main wires it live.
- i18n en/es/pt (market.*), reuses share.* for type labels.

3 market widget tests + home tests green; app_seeds analyzes clean.

apps/app_seeds/lib/ui/home_screen.dart

@@ -11,7 +11,11 @@ import 'theme.dart';
 /// to action and "Open market" (Block 2) as a disabled outlined card. The
 /// hamburger opens [AppDrawer].
 class HomeScreen extends StatelessWidget {
-  const HomeScreen({super.key});
+  const HomeScreen({this.marketEnabled = false, super.key});
+
+  /// When the Block 2 social layer is wired, the market becomes a live
+  /// destination; otherwise it stays a disabled "coming soon" card.
+  final bool marketEnabled;
 
   @override
   Widget build(BuildContext context) {
@@ -77,10 +81,14 @@ class HomeScreen extends StatelessWidget {
                     ),
                     const SizedBox(height: 16),
                     _OutlinedMenuCard(
+                      key: const Key('home.market'),
                       icon: Icons.storefront_outlined,
                       label: t.home.openMarket,
                       subtitle: t.home.openMarketSubtitle,
-                      tag: t.common.comingSoon,
+                      tag: marketEnabled ? null : t.common.comingSoon,
+                      onTap: marketEnabled
+                          ? () => context.go('/market')
+                          : null,
                     ),
                   ],
                 ),
@@ -151,17 +159,24 @@ class _OutlinedMenuCard extends StatelessWidget {
     required this.icon,
     required this.label,
     required this.subtitle,
-    required this.tag,
+    this.tag,
+    this.onTap,
+    super.key,
   });
 
   final IconData icon;
   final String label;
   final String subtitle;
-  final String tag;
+
+  /// A small trailing tag (e.g. "coming soon"); omitted for live cards.
+  final String? tag;
+
+  /// When set, the card is tappable; otherwise it reads as disabled.
+  final VoidCallback? onTap;
 
   @override
   Widget build(BuildContext context) {
-    return Container(
+    final card = Container(
       decoration: BoxDecoration(
         color: Colors.white,
         borderRadius: BorderRadius.circular(18),
@@ -183,18 +198,31 @@ class _OutlinedMenuCard extends StatelessWidget {
               subtitleColor: seedMuted,
             ),
           ),
-          Text(
-            tag.toUpperCase(),
-            style: const TextStyle(
-              color: Color(0xFFB3BDA8),
-              fontSize: 11,
-              fontWeight: FontWeight.w500,
-              letterSpacing: 0.5,
-            ),
-          ),
+          if (tag != null)
+            Text(
+              tag!.toUpperCase(),
+              style: const TextStyle(
+                color: Color(0xFFB3BDA8),
+                fontSize: 11,
+                fontWeight: FontWeight.w500,
+                letterSpacing: 0.5,
+              ),
+            )
+          else if (onTap != null)
+            const Icon(Icons.chevron_right, color: seedMuted),
         ],
       ),
     );
+    if (onTap == null) return card;
+    return Material(
+      color: Colors.transparent,
+      borderRadius: BorderRadius.circular(18),
+      child: InkWell(
+        onTap: onTap,
+        borderRadius: BorderRadius.circular(18),
+        child: card,
+      ),
+    );
   }
 }