fix: refresh Access Settings policy from /access response

Reopening the Access Settings dialog after a save could leave the
radio on the wrong policy: the form initialized `access_policy`
from the route list's snapshot, but the list isn't refreshed when
the dialog closes, so the snapshot's value silently shadowed the
just-saved policy.

Backend now returns the route's authoritative `access_policy` on
`GET /v2/model-routes/{id}/access`. Use that value when the GET
resolves, falling back to the parent snapshot only as the initial
seed so the radio isn't briefly unselected.

While we're here, widen the `access_policy` type from a closed
union to `string` — plugins can contribute additional policy
values via the `accessControl.allowedUsersOverride` slot, so the
wire type shouldn't restrict to the OSS-side enum.

src/pages/llmodels/components/access-control-modal/form.tsx

@@ -221,6 +221,10 @@ const AccessControlForm = forwardRef((props: AccessControlFormProps, ref) => {
       const userMap = new Map(allusers.map((u) => [u.key, u]));
 
       if (currentData?.id) {
+        // Seed the radio from the parent's snapshot so the form isn't
+        // momentarily unselected; the GET below replaces it with the
+        // server's authoritative value, which is what survives a save
+        // when the parent list hasn't been refreshed.
         form.setFieldsValue({
           access_policy: currentData?.access_policy
         });
@@ -246,7 +250,7 @@ const AccessControlForm = forwardRef((props: AccessControlFormProps, ref) => {
           setFilterInUsers(filterSet);
 
           form.setFieldsValue({
-            access_policy: currentData.access_policy,
+            access_policy: res.access_policy ?? currentData.access_policy,
             users: res.items.map((item) => ({ id: item.id }))
           });
         });

src/pages/llmodels/components/access-control-modal/index.tsx

@@ -23,7 +23,7 @@ const AccessControlModal: React.FC<
 
   const handleOnFinish = async (values: AccessControlFormData) => {
     try {
-      const data: any = {
+      const data: AccessControlFormData = {
         access_policy: values.access_policy,
         // `users` is only meaningful for the legacy `allowed_users`
         // policy; for the plugin override (typically the principal-