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/designs/input/CountStepper.dart

@@ -56,8 +56,8 @@ Widget _stepButton(IconData icon, VoidCallback? onTap) {
         color: enabled ? colorSecondary : colorInset,
         borderRadius: BorderRadius.circular(10),
       ),
-      child: Icon(icon,
-          size: 14, color: enabled ? colorPrimaryDark : colorGrey),
+      child:
+          Icon(icon, size: 14, color: enabled ? colorPrimaryDark : colorGrey),
     ),
   );
 }

frontend/lib/Grounded/designs/input/InputFields.dart

@@ -46,9 +46,8 @@ Widget inputField(
             fontSize: 13,
             color: colorGrey,
           ),
-          prefixIcon: icon == null
-              ? null
-              : Icon(icon, size: 18, color: colorGrey2),
+          prefixIcon:
+              icon == null ? null : Icon(icon, size: 18, color: colorGrey2),
           filled: true,
           fillColor: colorWhite,
           contentPadding: