feat(initial): add comprehensive PDF to JPEG preview library with dual-environment support

- Add Node.js implementation using @push.rocks/smartpdf
- Add browser implementation with PDF.js and Web Workers
- Support configurable quality, dimensions, and page selection
- Include comprehensive TypeScript definitions and error handling
- Provide extensive test coverage for both environments
- Add download functionality and browser compatibility checking

test/test.browser.ts

@@ -0,0 +1,196 @@
+import { expect, tap } from '@git.zone/tstest/tapbundle';
+import * as smartpreview from '../ts_web/index.ts';
+
+// Test data - minimal PDF as Uint8Array for browser testing
+const createMinimalPdfBuffer = (): Uint8Array => {
+  const pdfContent = `%PDF-1.4
+1 0 obj
+<<
+/Type /Catalog
+/Pages 2 0 R
+>>
+endobj
+
+2 0 obj
+<<
+/Type /Pages
+/Kids [3 0 R]
+/Count 1
+>>
+endobj
+
+3 0 obj
+<<
+/Type /Page
+/Parent 2 0 R
+/MediaBox [0 0 612 792]
+/Resources <<
+/Font <<
+/F1 4 0 R
+>>
+>>
+/Contents 5 0 R
+>>
+endobj
+
+4 0 obj
+<<
+/Type /Font
+/Subtype /Type1
+/BaseFont /Helvetica
+>>
+endobj
+
+5 0 obj
+<<
+/Length 44
+>>
+stream
+BT
+/F1 12 Tf
+72 720 Td
+(Hello World) Tj
+ET
+endstream
+endobj
+
+xref
+0 6
+0000000000 65535 f 
+0000000010 00000 n 
+0000000079 00000 n 
+0000000136 00000 n 
+0000000273 00000 n 
+0000000362 00000 n 
+trailer
+<<
+/Size 6
+/Root 1 0 R
+>>
+startxref
+456
+%%EOF`;
+  
+  return new TextEncoder().encode(pdfContent);
+};
+
+// Create a mock File object for testing
+const createMockPdfFile = (): File => {
+  const buffer = createMinimalPdfBuffer();
+  return new File([buffer], 'test.pdf', { type: 'application/pdf' });
+};
+
+tap.test('should check browser compatibility', async () => {
+  const compatibility = smartpreview.SmartPreview.getBrowserCompatibility();
+  
+  expect(compatibility).toHaveProperty('fileApi');
+  expect(compatibility).toHaveProperty('webWorkers');
+  expect(compatibility).toHaveProperty('offscreenCanvas');
+  expect(compatibility).toHaveProperty('isSupported');
+  
+  expect(typeof compatibility.fileApi).toEqual('boolean');
+  expect(typeof compatibility.webWorkers).toEqual('boolean');
+  expect(typeof compatibility.offscreenCanvas).toEqual('boolean');
+  expect(typeof compatibility.isSupported).toEqual('boolean');
+});
+
+tap.test('should create SmartPreview instance', async () => {
+  const preview = new smartpreview.SmartPreview();
+  expect(preview).toBeInstanceOf(smartpreview.SmartPreview);
+});
+
+tap.test('should return supported formats', async () => {
+  const preview = new smartpreview.SmartPreview();
+  const formats = preview.getSupportedFormats();
+  
+  expect(formats).toContain('pdf');
+  expect(preview.isFormatSupported('pdf')).toEqual(true);
+  expect(preview.isFormatSupported('jpg')).toEqual(false);
+});
+
+tap.test('should throw error when not initialized', async () => {
+  const preview = new smartpreview.SmartPreview();
+  const testFile = createMockPdfFile();
+
+  try {
+    await preview.generatePreview(testFile);
+    expect(true).toEqual(false); // Should not reach here
+  } catch (error) {
+    expect(error).toBeInstanceOf(smartpreview.PreviewError);
+    expect(error.errorType).toEqual('PROCESSING_FAILED');
+  }
+});
+
+tap.test('should validate input', async () => {
+  const preview = new smartpreview.SmartPreview();
+  
+  try {
+    await preview.generatePreview(null as any);
+    expect(true).toEqual(false); // Should not reach here
+  } catch (error) {
+    expect(error).toBeInstanceOf(smartpreview.PreviewError);
+    expect(error.errorType).toEqual('PROCESSING_FAILED');
+  }
+});
+
+tap.test('should handle initialization', async () => {
+  const preview = new smartpreview.SmartPreview();
+  
+  try {
+    await preview.init();
+    expect(true).toEqual(true); // If we get here, init succeeded
+  } catch (error) {
+    // Expected if browser APIs are not fully available in test environment
+    expect(error).toBeInstanceOf(smartpreview.PreviewError);
+  } finally {
+    await preview.cleanup();
+  }
+});
+
+tap.test('should create PreviewError correctly', async () => {
+  const error = new smartpreview.PreviewError('INVALID_INPUT', 'Test error message');
+  
+  expect(error).toBeInstanceOf(Error);
+  expect(error).toBeInstanceOf(smartpreview.PreviewError);
+  expect(error.errorType).toEqual('INVALID_INPUT');
+  expect(error.message).toEqual('Test error message');
+  expect(error.name).toEqual('PreviewError');
+});
+
+tap.test('should handle different input types', async () => {
+  // Test with File
+  const file = createMockPdfFile();
+  expect(file).toBeInstanceOf(File);
+  expect(file.type).toEqual('application/pdf');
+  
+  // Test with ArrayBuffer
+  const buffer = createMinimalPdfBuffer();
+  const arrayBuffer = buffer.buffer.slice(buffer.byteOffset, buffer.byteOffset + buffer.byteLength);
+  expect(arrayBuffer).toBeInstanceOf(ArrayBuffer);
+  
+  // Test with Uint8Array
+  expect(buffer).toBeInstanceOf(Uint8Array);
+});
+
+tap.test('should provide download functionality methods', async () => {
+  const preview = new smartpreview.SmartPreview();
+  
+  // These methods should exist
+  expect(typeof preview.createDownloadLink).toEqual('function');
+  expect(typeof preview.downloadPreview).toEqual('function');
+  expect(typeof preview.generatePreviewFromFile).toEqual('function');
+  expect(typeof preview.generatePreviewFromUrl).toEqual('function');
+});
+
+tap.test('should create instance via factory method', async () => {
+  try {
+    const preview = await smartpreview.SmartPreview.create();
+    expect(preview).toBeInstanceOf(smartpreview.SmartPreview);
+    await preview.cleanup();
+  } catch (error) {
+    // Expected if browser APIs are not fully available
+    expect(error).toBeInstanceOf(smartpreview.PreviewError);
+  }
+});
+
+export default tap.start();