fix: Index.fts({ withPosition: true }) to enable phrase queries

Fix BM25 search failure: position is not found but required for phrase queries

Root cause: Index.fts() accepts an options object, not a boolean.
Index.fts(true) sets options=true, so options?.withPosition is undefined.

Fix: use Index.fts({ withPosition: true }) instead.

Fixes: #402

Author: jlin53882

src/store.ts

@@ -362,7 +362,7 @@ export class MemoryStore {
         // LanceDB @lancedb/lancedb >=0.26: use Index.fts() config
         const lancedb = await loadLanceDB();
         await table.createIndex("text", {
-          config: (lancedb as any).Index.fts(),
+          config: (lancedb as any).Index.fts({ withPosition: true }),
         });
       }
     } catch (err) {