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/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,