feat: add telegram-style resource stream

src/pages/PostRedirect.tsx

@@ -0,0 +1,30 @@
+import { useEffect } from "react";
+import { Navigate, useParams } from "react-router-dom";
+import { MOCK_POSTS } from "../mocks/mockPosts";
+import { POST_STREAM_USES_MOCK } from "../components/messageStream/hooks/usePostStream";
+
+export function PostRedirect() {
+  const { id } = useParams();
+  // Real-API branch placeholder: when backend ships /api/posts/:id, fetch and
+  // navigate to /category/<categorySlug>#post-<id>. For now mock lookup.
+  const post = id ? MOCK_POSTS.find((p) => p.id === id) : undefined;
+
+  useEffect(() => {
+    if (post) {
+      requestAnimationFrame(() => {
+        document
+          .getElementById(`post-${post.id}`)
+          ?.scrollIntoView({ behavior: "smooth", block: "center" });
+      });
+    }
+  }, [post]);
+
+  if (!POST_STREAM_USES_MOCK && !post) {
+    // TODO: replace with real fetch when /api/posts/:id ships.
+    return <Navigate to="/browse" replace />;
+  }
+  if (!post) return <Navigate to="/browse" replace />;
+  return (
+    <Navigate to={`/category/${post.categorySlug}#post-${post.id}`} replace />
+  );
+}