fix(build): align TypeScript and test imports with NodeNext builds and safely copy Uint8Array inputs in browser processing

test/test.node.ts

@@ -1,5 +1,5 @@
 import { expect, tap } from '@git.zone/tstest/tapbundle';
-import * as smartpreview from '../ts/index.ts';
+import * as smartpreview from '../ts/index.js';
 
 // Test data - minimal PDF buffer for testing
 const createMinimalPdf = (): Buffer => {
@@ -105,6 +105,9 @@ tap.test('should throw error when not initialized', async () => {
     expect(true).toEqual(false); // Should not reach here
   } catch (error) {
     expect(error).toBeInstanceOf(smartpreview.PreviewError);
+    if (!(error instanceof smartpreview.PreviewError)) {
+      throw error;
+    }
     expect(error.errorType).toEqual('PROCESSING_FAILED');
   }
 });
@@ -117,6 +120,9 @@ tap.test('should validate input buffer', async () => {
     expect(true).toEqual(false); // Should not reach here
   } catch (error) {
     expect(error).toBeInstanceOf(smartpreview.PreviewError);
+    if (!(error instanceof smartpreview.PreviewError)) {
+      throw error;
+    }
     expect(error.errorType).toEqual('PROCESSING_FAILED');
   }
 });