fix: generate presigned avatar URLs for card members on board view (#388)

The board.byId query was generating presigned S3 URLs for workspace
member avatars but not for card member avatars. This caused card avatars
to silently fall back to initials since the frontend helper returns ""
for raw S3 keys.

Closes #387

Co-authored-by: Claude Opus 4.6 <noreply@anthropic.com>

packages/api/src/routers/board.ts

@@ -173,8 +173,31 @@ export const boardRouter = createTRPCRouter({
           }
         : result.workspace;
 
+      // Generate presigned URLs for card member avatars
+      const listsWithAvatarUrls = await Promise.all(
+        result.lists.map(async (list) => ({
+          ...list,
+          cards: await Promise.all(
+            list.cards.map(async (card) => ({
+              ...card,
+              members: await Promise.all(
+                card.members.map(async (member) => {
+                  if (!member.user?.image) return member;
+                  const avatarUrl = await generateAvatarUrl(member.user.image);
+                  return {
+                    ...member,
+                    user: { ...member.user, image: avatarUrl },
+                  };
+                }),
+              ),
+            })),
+          ),
+        })),
+      );
+
       return {
         ...result,
+        lists: listsWithAvatarUrls,
         workspace: workspaceWithAvatarUrls,
       };
     }),