fix ensureIndex

Author: mrlynn

src/core/IndexManager.js

@@ -56,6 +56,10 @@ class IndexManager {
         }
     }
 
+    async ensureIndex() {
+        return this.ensureIndexes();
+    }
+
     async createSupportingIndexes() {
         try {
             await this.collection.createIndex(

src/core/MongoRAG.js

@@ -153,7 +153,7 @@ class MongoRAG {
             });
 
             // Ensure the index is created
-            await indexManager.ensureIndex();
+            await indexManager.ensureIndexes();
 
             // Construct the vector search query using the $vectorSearch operator
             const aggregation = query