fix: favorites click opens isolated single-post view

When `linkToResource` is set, PopularRankRow now navigates to /resource/<id>?single=1 and PostRedirect propagates the `single=1` flag to the /browse?post=... target. MessageStream already supports singlePostMode (no filter bar, no sentinel, only the target post in the list), so favorites cards open the post in isolation instead of dropping the user into the surrounding stream.

src/components/PopularRankList.tsx

@@ -150,7 +150,7 @@ export function PopularRankRow({
         type="button"
         onClick={() => {
           if (linkToResource) {
-            navigate(lp(`/resource/${encodeURIComponent(post.id)}`));
+            navigate(lp(`/resource/${encodeURIComponent(post.id)}?single=1`));
             return;
           }
           const params = new URLSearchParams();