fix: server settings groups tab visible to owner

Server interface had 'ownerId' (camelCase) but API returns
'owner_id' (snake_case). isOwner was always false, hiding
groups/roles/audit tabs for the server owner.

web/src/stores/server.ts

@@ -5,7 +5,7 @@ export interface Server {
   id: string;
   name: string;
   icon: string | null;
-  ownerId: string;
+  owner_id: string;
   unread?: boolean;
 }