fix(pre-auth-keys): pass Headscale numeric user id when expiring on 0.27.x

The pre-0.28 ExpirePreAuthKey RPC takes a uint64 `user` field plus the
key string. The API layer reads that uint64 from `key.user?.id`, but
the action was wrapping the form's user_id as `{ name: user }` — so
.id was always undefined and the wire request sent an empty string,
which Headscale rejects with "proto: invalid value for uint64 field
user". 0.28+ is unaffected because the new expire endpoint only reads
`key.id` (the stable preauthkey id).

Pass `{ id: user }` so the numeric Headscale user id reaches the wire.

Amp-Thread-ID: https://ampcode.com/threads/T-019e7ae4-6862-760c-a3e7-239350eab71d
Co-authored-by: Amp <amp@ampcode.com>

app/routes/settings/auth-keys/actions.ts

@@ -112,10 +112,14 @@ export async function authKeysAction({ request, context }: Route.ActionArgs) {
       }
 
       await checkSelfServiceOwnership(user);
+      // `user` here is the Headscale numeric user id (form field is wired
+      // from User.id). Pre-0.28 expire posts a uint64 `user` field, which
+      // the API layer reads from `key.user?.id`. Headscale 0.28+ only
+      // looks at `key.id` (the stable preauthkey id).
       await api.preAuthKeys.expire({
         id: keyId,
         key,
-        user: { name: user },
+        user: { id: user },
       } as unknown as PreAuthKey);
       return data("Pre-auth key expired");
     }