feat(profile): show other people's avatars in chat, chat list, your people

Follow-up to the avatar feature: peers' published photos/illustrations
now actually render where people appear.

- CachedAvatar: a PeerAvatar that resolves the person's picture from the
  ProfileCache (FutureBuilder), falling back to the coloured-initial disc.
  For list/row sites — one avatar each.
- Chat bubbles: the peer's and my own avatar are resolved once into state
  (_peerPicture/_selfPicture — from the cache / ProfileStore, freshened
  from the peer's published profile) and threaded to each bubble, so many
  bubbles of two people don't each hit the cache.
- Chat list + your-people rows: swapped the static person-icon disc for
  CachedAvatar, so photos/illustrations show there too.
- Tests: CachedAvatar render modes (cached illustration / initial / no
  cache). analyze clean; chat + your-people suites green.

Market offers show no author avatar today (would be a new element, not a
swap) — left out of scope.

apps/app_seeds/lib/ui/chat_screen.dart

@@ -60,6 +60,8 @@ class _ChatScreenState extends State<ChatScreen> {
   bool _loading = true;
   String? _peerName;
   String? _selfName;
+  String? _peerPicture;
+  String? _selfPicture;
   String? _peerG1;
   final _input = TextEditingController();
 
@@ -86,10 +88,13 @@ class _ChatScreenState extends State<ChatScreen> {
     // connected / unreachable) → null transports and the screen degrades.
     final session = await widget.connection.session();
     final cachedName = await widget.profileCache?.name(widget.peerPubkey);
-    // My own display name, so my avatar shows my initial (not a bare glyph).
-    final selfName = getIt.isRegistered<ProfileStore>()
-        ? await getIt<ProfileStore>().name()
-        : '';
+    final cachedPicture = await widget.profileCache?.picture(widget.peerPubkey);
+    // My own name + avatar, so my side shows me (not a bare glyph).
+    final selfStore = getIt.isRegistered<ProfileStore>()
+        ? getIt<ProfileStore>()
+        : null;
+    final selfName = selfStore == null ? '' : await selfStore.name();
+    final selfAvatar = selfStore == null ? '' : await selfStore.avatar();
     if (!mounted) return; // shared session is owned by the connection, not us
     final self = widget.social.publicKeyHex;
     final messages = MessagesCubit(
@@ -117,6 +122,8 @@ class _ChatScreenState extends State<ChatScreen> {
       _rating = rating;
       _peerName = cachedName;
       _selfName = selfName.isEmpty ? null : selfName;
+      _peerPicture = cachedPicture;
+      _selfPicture = selfAvatar.isEmpty ? null : selfAvatar;
       _loading = false;
     });
 
@@ -133,8 +140,15 @@ class _ChatScreenState extends State<ChatScreen> {
                 profile.name,
               );
             }
+            if (profile.picture.isNotEmpty) {
+              await widget.profileCache!.setPicture(
+                widget.peerPubkey,
+                profile.picture,
+              );
+            }
             setState(() {
               if (profile.name.isNotEmpty) _peerName = profile.name;
+              if (profile.picture.isNotEmpty) _peerPicture = profile.picture;
               if (profile.g1.isNotEmpty) _peerG1 = profile.g1;
             });
           }
@@ -230,6 +244,8 @@ class _ChatScreenState extends State<ChatScreen> {
                 onSend: _send,
                 peerName: _peerName,
                 selfName: _selfName,
+                peerPicture: _peerPicture,
+                selfPicture: _selfPicture,
               ),
             ),
     );
@@ -242,12 +258,16 @@ class _ChatBody extends StatelessWidget {
     required this.onSend,
     this.peerName,
     this.selfName,
+    this.peerPicture,
+    this.selfPicture,
   });
 
   final TextEditingController controller;
   final Future<void> Function() onSend;
   final String? peerName;
   final String? selfName;
+  final String? peerPicture;
+  final String? selfPicture;
 
   @override
   Widget build(BuildContext context) {
@@ -278,7 +298,12 @@ class _ChatBody extends StatelessWidget {
           const _TrustBanner(),
           const _RatingStrip(),
           Expanded(
-            child: ChatMessageList(peerName: peerName, selfName: selfName),
+            child: ChatMessageList(
+              peerName: peerName,
+              selfName: selfName,
+              peerPicture: peerPicture,
+              selfPicture: selfPicture,
+            ),
           ),
           _Composer(controller: controller, onSend: onSend),
         ],
@@ -292,7 +317,13 @@ class _ChatBody extends StatelessWidget {
 /// in place instead of landing below the fold. Reads the [MessagesCubit] from
 /// context.
 class ChatMessageList extends StatelessWidget {
-  const ChatMessageList({this.peerName, this.selfName, super.key});
+  const ChatMessageList({
+    this.peerName,
+    this.selfName,
+    this.peerPicture,
+    this.selfPicture,
+    super.key,
+  });
 
   /// The peer's display name, for their avatar's initial (null → a glyph).
   final String? peerName;
@@ -300,6 +331,10 @@ class ChatMessageList extends StatelessWidget {
   /// My own display name, for my avatar's initial (null → a glyph).
   final String? selfName;
 
+  /// The peer's / my published avatar (null → the coloured-initial disc).
+  final String? peerPicture;
+  final String? selfPicture;
+
   @override
   Widget build(BuildContext context) {
     final t = context.t;
@@ -329,6 +364,8 @@ class ChatMessageList extends StatelessWidget {
                 mine: cubit.isMine(message),
                 peerName: peerName,
                 selfName: selfName,
+                peerPicture: peerPicture,
+                selfPicture: selfPicture,
                 selfPubkey: cubit.selfPubkey,
               ),
             };
@@ -494,6 +531,8 @@ class _MessageRow extends StatelessWidget {
     required this.mine,
     this.peerName,
     this.selfName,
+    this.peerPicture,
+    this.selfPicture,
     this.selfPubkey,
   });
 
@@ -501,17 +540,27 @@ class _MessageRow extends StatelessWidget {
   final bool mine;
   final String? peerName;
   final String? selfName;
+  final String? peerPicture;
+  final String? selfPicture;
 
   /// My own pubkey, so my messages carry my (distinctly coloured) avatar.
   final String? selfPubkey;
 
   @override
   Widget build(BuildContext context) {
-    // Each avatar shows its owner's initial (falling back to a glyph when no
-    // name is known) on a colour derived from their pubkey.
+    // Each avatar shows its owner's photo/illustration when set, else their
+    // initial (or a glyph) on a colour derived from their pubkey.
     final avatar = mine
-        ? PeerAvatar(pubkey: selfPubkey ?? message.fromPubkey, name: selfName)
-        : PeerAvatar(pubkey: message.fromPubkey, name: peerName);
+        ? PeerAvatar(
+            pubkey: selfPubkey ?? message.fromPubkey,
+            name: selfName,
+            picture: selfPicture,
+          )
+        : PeerAvatar(
+            pubkey: message.fromPubkey,
+            name: peerName,
+            picture: peerPicture,
+          );
     final bubble = Flexible(
       child: _Bubble(message: message, mine: mine),
     );