QdrantSearch: Add query prefix.

lib/pleroma/search/qdrant_search.ex

@@ -71,6 +71,8 @@ def add_to_index(activity) do
 
   @impl true
   def search(_user, query, _options) do
+    query = "Represent this sentence for searching relevant passages: #{query}"
+
     with {:ok, embedding} <- get_embedding(query),
          {:ok, %{body: %{"result" => result}}} <-
            QdrantClient.post("/collections/posts/points/search", build_search_payload(embedding)) do