feat: add admin user edit page with avatar, banner, and photo gallery

- Backend: adminGetUser query returns user + photos; adminUpdateUser now
  accepts avatarId/bannerId; new adminAddUserPhoto and adminRemoveUserPhoto
  mutations; AdminUserDetailType added to GraphQL schema
- Frontend: /admin/users/[id] page for editing name, avatar, banner, and
  managing the model photo gallery (upload multiple, delete individually)
- Admin users list: edit button per row linking to the detail page

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

packages/frontend/src/routes/admin/users/+page.svelte

@@ -160,15 +160,20 @@
             </td>
             <td class="px-4 py-3 text-muted-foreground">{formatDate(user.date_created)}</td>
             <td class="px-4 py-3 text-right">
-              <Button
-                size="sm"
-                variant="ghost"
-                class="text-destructive hover:text-destructive hover:bg-destructive/10"
-                disabled={user.id === currentUserId}
-                onclick={() => confirmDelete(user)}
-              >
-                <span class="icon-[ri--delete-bin-line] h-4 w-4"></span>
-              </Button>
+              <div class="flex items-center justify-end gap-1">
+                <Button size="sm" variant="ghost" href="/admin/users/{user.id}">
+                  <span class="icon-[ri--edit-line] h-4 w-4"></span>
+                </Button>
+                <Button
+                  size="sm"
+                  variant="ghost"
+                  class="text-destructive hover:text-destructive hover:bg-destructive/10"
+                  disabled={user.id === currentUserId}
+                  onclick={() => confirmDelete(user)}
+                >
+                  <span class="icon-[ri--delete-bin-line] h-4 w-4"></span>
+                </Button>
+              </div>
             </td>
           </tr>
         {/each}