Show real photos for people instead of scene art

Your avatar is your photo, picked from the device by tapping it on Home or
from a new Profile photo row in Settings, shrunk to 256 px and kept on the
phone (there is no upload endpoint yet). Group members show the photo the
server sends in a new `photo` field, everywhere avatars appear. Without a
photo, an initial on a neutral disc. Mock mode bundles free Unsplash
portraits for the sample people.

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01KhQh614DMeYoQEH9SoMRUw

frontend/lib/Grounded/see/group/GroupChatState.dart

@@ -98,6 +98,16 @@ class GroupChatState extends State<GroupChat> implements ConnectGroupChat {
     _onSend(reply);
   }
 
+  /// A message author's photo, looked up among the group's members.
+  String _photoOf(String authorId) {
+    for (final member in widget.group.members) {
+      if (member.id == authorId) {
+        return member.photo;
+      }
+    }
+    return "";
+  }
+
   // ── Views ─────────────────────────────────────────────────────────────────
 
   Widget _mobileView(BoxConstraints constraints) {
@@ -145,8 +155,7 @@ class GroupChatState extends State<GroupChat> implements ConnectGroupChat {
 
     return Container(
       decoration: BoxDecoration(
-        borderRadius:
-            const BorderRadius.vertical(bottom: Radius.circular(20)),
+        borderRadius: const BorderRadius.vertical(bottom: Radius.circular(20)),
         gradient: LinearGradient(
           begin: Alignment.topLeft,
           end: Alignment.bottomRight,
@@ -188,7 +197,10 @@ class GroupChatState extends State<GroupChat> implements ConnectGroupChat {
           const SizedBox(width: 10),
           avatarStack(
               widget.group.members.map((member) => member.name).toList(), 30,
-              max: 3, border: colorNight),
+              photos:
+                  widget.group.members.map((member) => member.photo).toList(),
+              max: 3,
+              border: colorNight),
         ],
       ),
     );
@@ -275,7 +287,8 @@ class GroupChatState extends State<GroupChat> implements ConnectGroupChat {
         children: [
           grouped
               ? const SizedBox(width: 34)
-              : memberAvatar(message.authorName, 34),
+              : memberAvatar(message.authorName, 34,
+                  photo: _photoOf(message.authorId)),
           const SizedBox(width: 8),
           Flexible(
             child: Container(
@@ -328,7 +341,8 @@ class GroupChatState extends State<GroupChat> implements ConnectGroupChat {
         ),
         child: Row(
           children: [
-            memberAvatar(message.authorName, 34),
+            memberAvatar(message.authorName, 34,
+                photo: _photoOf(message.authorId)),
             const SizedBox(width: 12),
             Expanded(
               child: Column(

frontend/lib/Grounded/see/group/GroupDetailState.dart

@@ -329,7 +329,8 @@ class GroupDetailState extends State<GroupDetail>
                               horizontal: 7, vertical: 3),
                           decoration: BoxDecoration(
                             color: colorLime,
-                            borderRadius: const BorderRadius.all(Radius.circular(8)),
+                            borderRadius:
+                                const BorderRadius.all(Radius.circular(8)),
                           ),
                           child: text(
                               "${_group.unread} new", 10, TextType.Medium,
@@ -519,7 +520,7 @@ class GroupDetailState extends State<GroupDetail>
               child: text("$rank", 16, TextType.Medium,
                   color: rank == 1 ? colorInk : colorGrey2),
             ),
-            memberAvatar(member.name, 46),
+            memberAvatar(member.name, 46, photo: member.photo),
             const SizedBox(width: 12),
             Expanded(
               child: Column(
@@ -632,7 +633,8 @@ class GroupDetailState extends State<GroupDetail>
                       alignment: Alignment.center,
                       decoration: BoxDecoration(
                         color: colorAmbientMid,
-                        borderRadius: const BorderRadius.all(Radius.circular(12)),
+                        borderRadius:
+                            const BorderRadius.all(Radius.circular(12)),
                       ),
                       child: text(
                           "+${formatAmount(preset)}", 15, TextType.Medium,

frontend/lib/Grounded/see/group/GroupEditorState.dart

@@ -245,7 +245,7 @@ class GroupEditorState extends State<GroupEditor>
           text(name, 26, TextType.Light,
               color: colorWhite, maxLines: 2, overflow: TextOverflow.ellipsis),
           const SizedBox(height: 16),
-          avatarStack(const <String>["Alex"], 34),
+          avatarStack(const <String>["You"], 34),
         ],
       ),
     );

frontend/lib/Grounded/see/group/GroupsState.dart

@@ -180,7 +180,8 @@ class GroupsState extends State<Groups> implements ConnectGroups {
                               horizontal: 10, vertical: 6),
                           decoration: BoxDecoration(
                             color: colorLime,
-                            borderRadius: const BorderRadius.all(Radius.circular(8)),
+                            borderRadius:
+                                const BorderRadius.all(Radius.circular(8)),
                           ),
                           child: Row(
                             mainAxisSize: MainAxisSize.min,
@@ -218,7 +219,10 @@ class GroupsState extends State<Groups> implements ConnectGroups {
                     children: [
                       avatarStack(
                           group.members.map((member) => member.name).toList(),
-                          32),
+                          32,
+                          photos: group.members
+                              .map((member) => member.photo)
+                              .toList()),
                       const Spacer(),
                       text("${(group.progress * 100).round()}%", 22,
                           TextType.Light,