Fix ESM import error for @xenova/transformers

Change static import to dynamic import() for @xenova/transformers
which is an ESM-only package. This fixes ERR_REQUIRE_ESM when
running via npx in CommonJS environments.

Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>

src/vectors/embedder.ts

@@ -5,12 +5,22 @@
  * Uses ONNX runtime under the hood for fast local inference.
  */
 
-import { pipeline, env } from '@xenova/transformers';
 import * as path from 'path';
 import * as fs from 'fs';
 
+// Dynamic import for @xenova/transformers (ESM-only package)
+// We use dynamic import to support CommonJS builds
+let transformersModule: typeof import('@xenova/transformers') | null = null;
+
+async function getTransformers() {
+  if (!transformersModule) {
+    transformersModule = await import('@xenova/transformers');
+  }
+  return transformersModule;
+}
+
 // Type for the feature extraction pipeline
-type FeatureExtractionPipeline = Awaited<ReturnType<typeof pipeline<'feature-extraction'>>>;
+type FeatureExtractionPipeline = any;
 
 /**
  * Default model for embeddings
@@ -93,6 +103,9 @@ export class TextEmbedder {
       return;
     }
 
+    // Load transformers.js dynamically (ESM-only package)
+    const { pipeline, env } = await getTransformers();
+
     // Configure transformers.js to use local cache
     env.cacheDir = this.cacheDir;