Adopt shared WebUI structural primitives

webui/src/features/admin/SystemUsersPanel.tsx

@@ -1,4 +1,4 @@
-import { DescriptionItem, DescriptionList } from "@govoplan/core-webui";
+import { ContentGrid, DescriptionItem, DescriptionList } from "@govoplan/core-webui";
 import { useEffect, useMemo, useRef, useState } from "react";
 import { Search, Pencil, Plus, Trash2 } from "lucide-react";
 import type { FormGrid, ApiSettings } from "@govoplan/core-webui";
@@ -250,10 +250,10 @@ export default function SystemUsersPanel({
           }
           <FormField label="i18n:govoplan-access.account_status.8dd86c6d"><select value={draft.isActive ? "active" : "inactive"} disabled={Boolean(editing && editing !== "new" && (!canSuspend || editing.memberships.some((membership) => membership.is_last_active_owner)))} onChange={(event) => setDraft({ ...draft, isActive: event.target.value === "active" })}><option value="active">i18n:govoplan-access.active.a733b809</option><option value="inactive">i18n:govoplan-access.inactive.09af574c</option></select></FormField>
         </FormGrid>
-        <div className="admin-assignment-grid">
+        <ContentGrid columns={2} spacing="block" collapseAt="wide">
           <div><span className="form-label">i18n:govoplan-access.system_roles.a9461aa6</span><AdminSelectionList options={roles.map((role) => ({ id: role.id, label: role.name, description: role.description, disabled: !canAssignRoles }))} selected={draft.roleIds} onChange={(roleIds) => setDraft({ ...draft, roleIds })} /></div>
           <div><span className="form-label">i18n:govoplan-access.tenant_memberships.451de736</span><AdminSelectionList options={tenants.map((tenant) => ({ id: tenant.id, label: tenant.name, description: tenant.slug, disabled: !canManageMemberships || Boolean(draft.memberships.find((item) => item.tenant_id === tenant.id)?.is_last_active_owner) }))} selected={draft.memberships.map((item) => item.tenant_id)} onChange={setMembershipSelection} /></div>
-        </div>
+        </ContentGrid>
         {editing && editing !== "new" && editing.memberships.some((membership) => membership.is_last_active_owner) && <p className="admin-protection-note">i18n:govoplan-access.this_account_is_the_last_active_operational_owne.5087839f</p>}
         <p className="muted small-note">i18n:govoplan-access.removing_a_tenant_checkbox_suspends_that_members.7c6df77d</p>
       </Dialog>