feat(backfill): implement backfill tool for generating missing embeddings

internal/tools/recall.go

@@ -48,17 +48,13 @@ func (t *RecallTool) Handle(ctx context.Context, req *mcp.CallToolRequest, in Re
 	}
 
 	limit := normalizeLimit(in.Limit, t.search)
-	embedding, err := t.provider.Embed(ctx, query)
-	if err != nil {
-		return nil, RecallOutput{}, err
-	}
 
 	var projectID *uuid.UUID
 	if project != nil {
 		projectID = &project.ID
 	}
 
-	semantic, err := t.store.SearchSimilarThoughts(ctx, embedding, t.provider.EmbeddingModel(), t.search.DefaultThreshold, limit, projectID, nil)
+	semantic, err := semanticSearch(ctx, t.store, t.provider, t.search, query, limit, t.search.DefaultThreshold, projectID, nil)
 	if err != nil {
 		return nil, RecallOutput{}, err
 	}