swarm-ui: the permissions box lists every permission instead of a narrow scroll area

The checkbox list was capped at 12em and scrolled, and the box shrinks the
list to its widest label, so the scrollbar sat in the middle of the popover
with the lower permissions hidden. The permissions are a short fixed list:
MultiselectFilterOptions takes scrollable={false} and the permissions box
uses it. Filter lists that can grow long keep the scroll area.

frontend/packages/swarm-ui/src/agent/detail/AgentPermissions.tsx

@@ -224,6 +224,7 @@ export function AgentPermissions({
               filter={{ values: ticked, negate: false }}
               onToggle={(v) => void toggle(v)}
               disabled={busy}
+              scrollable={false}
             />
           </div>
         ) : (