feat(ratings): Wallapop-style ratings in chat and offer detail

- SocialSession grows a ratings transport (fifth interface on the one
  shared channel).
- PeerRatingCubit: count, locale-aware average, and circleCount — how
  many ratings come from your own circle (reuses the ego-centric trust
  rule), the signal that makes strangers' review-stuffing irrelevant.
- Chat: slim rating strip under the trust banner; you can rate only
  someone you've talked with (soft anchor until the signed bilateral
  exchange form lands). Sheet with 5 stars + optional comment,
  pre-filled for editing, with a take-back action.
- Offer detail: author's stars under their name, with 'N from people
  you know' when your circle rated them; nothing shown when unrated.
- i18n ratings.* (en/es/pt/ast); tests for cubit and sheet.

apps/app_seeds/lib/ui/chat_screen.dart

@@ -15,8 +15,10 @@ import '../services/social_connection.dart';
 import '../services/social_service.dart';
 import '../services/unread_service.dart';
 import '../state/messages_cubit.dart';
+import '../state/peer_rating_cubit.dart';
 import '../state/trust_cubit.dart';
 import 'peer_avatar.dart';
+import 'rating_sheet.dart';
 import 'theme.dart';
 
 /// A 1:1 encrypted chat with one peer (redesign screen 10). Private and
@@ -52,6 +54,7 @@ class ChatScreen extends StatefulWidget {
 class _ChatScreenState extends State<ChatScreen> {
   MessagesCubit? _messages;
   TrustCubit? _trust;
+  PeerRatingCubit? _rating;
   bool _loading = true;
   String? _peerName;
   String? _peerG1;
@@ -94,9 +97,17 @@ class _ChatScreenState extends State<ChatScreen> {
       selfPubkey: self,
     );
     unawaited(trust.load());
+    final rating = PeerRatingCubit(
+      session?.ratings,
+      peerPubkey: widget.peerPubkey,
+      selfPubkey: self,
+      trust: session?.trust,
+    );
+    unawaited(rating.load());
     setState(() {
       _messages = messages;
       _trust = trust;
+      _rating = rating;
       _peerName = cachedName;
       _loading = false;
     });
@@ -166,6 +177,7 @@ class _ChatScreenState extends State<ChatScreen> {
     unawaited(_unread?.markRead(widget.peerPubkey));
     _messages?.close();
     _trust?.close();
+    _rating?.close();
     // The session belongs to the shared connection — don't close it here.
     _input.dispose();
     super.dispose();
@@ -175,6 +187,7 @@ class _ChatScreenState extends State<ChatScreen> {
   Widget build(BuildContext context) {
     final messages = _messages;
     final trust = _trust;
+    final rating = _rating;
     final t = context.t;
     return Scaffold(
       appBar: AppBar(
@@ -189,12 +202,13 @@ class _ChatScreenState extends State<ChatScreen> {
             ),
         ],
       ),
-      body: _loading || messages == null || trust == null
+      body: _loading || messages == null || trust == null || rating == null
           ? const Center(child: CircularProgressIndicator())
           : MultiBlocProvider(
               providers: [
                 BlocProvider.value(value: messages),
                 BlocProvider.value(value: trust),
+                BlocProvider.value(value: rating),
               ],
               child: _ChatBody(
                 controller: _input,
@@ -244,6 +258,7 @@ class _ChatBody extends StatelessWidget {
       child: Column(
         children: [
           const _TrustBanner(),
+          const _RatingStrip(),
           Expanded(child: ChatMessageList(peerName: peerName)),
           _Composer(controller: controller, onSend: onSend),
         ],
@@ -353,6 +368,56 @@ class _TrustBanner extends StatelessWidget {
   }
 }
 
+/// A slim reputation strip under the trust banner: everyone's stars for this
+/// peer (highlighting how many come from people you know) and, once you've
+/// actually talked with them, a button to leave or edit your own rating.
+class _RatingStrip extends StatelessWidget {
+  const _RatingStrip();
+
+  @override
+  Widget build(BuildContext context) {
+    final t = context.t;
+    return BlocBuilder<PeerRatingCubit, PeerRatingState>(
+      builder: (context, state) {
+        final cubit = context.read<PeerRatingCubit>();
+        if (!cubit.isOnline || state.loading) return const SizedBox.shrink();
+        // Soft anchor: you can only rate someone you've talked with.
+        final canRate = context.select<MessagesCubit, bool>(
+          (m) => m.state.messages.isNotEmpty,
+        );
+        if (!state.hasRatings && !canRate) return const SizedBox.shrink();
+        return Container(
+          width: double.infinity,
+          color: seedPrimaryContainer.withValues(alpha: 0.3),
+          padding: const EdgeInsetsDirectional.fromSTEB(16, 4, 8, 4),
+          child: Row(
+            children: [
+              Expanded(
+                child: state.hasRatings
+                    ? RatingStars(
+                        average: state.average,
+                        count: state.count,
+                        circleCount: state.circleCount,
+                      )
+                    : const SizedBox.shrink(),
+              ),
+              if (canRate)
+                TextButton(
+                  key: const Key('chat.rate'),
+                  onPressed: state.busy
+                      ? null
+                      : () => showRatingSheet(context, cubit),
+                  child:
+                      Text(state.iRated ? t.ratings.edit : t.ratings.rate),
+                ),
+            ],
+          ),
+        );
+      },
+    );
+  }
+}
+
 /// A centered pill introducing a new day ("Today", "Yesterday", or a
 /// locale-formatted date). Localized via [chatDayLabel].
 class _DaySeparator extends StatelessWidget {