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/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,