feat: add official Node.js and Python SDKs

- Node.js SDK (sdk/nodejs/): TypeScript, zero deps, native fetch, Node 18+
- Python SDK (sdk/python/): sync + async clients via httpx, Python 3.8+
- Both wrap all conversion endpoints (html, markdown, url, templates)
- Proper error handling with DocFastError
- Full README documentation for each

sdk/nodejs/README.md

@@ -0,0 +1,95 @@
+# DocFast Node.js SDK
+
+Official Node.js client for the [DocFast](https://docfast.dev) HTML-to-PDF API.
+
+## Install
+
+```bash
+npm install docfast
+```
+
+Requires Node.js 18+ (uses native `fetch`). Zero runtime dependencies.
+
+## Quick Start
+
+```typescript
+import DocFast from 'docfast';
+
+const client = new DocFast('df_pro_your_api_key');
+
+// HTML to PDF
+const pdf = await client.html('<h1>Hello World</h1>');
+fs.writeFileSync('output.pdf', pdf);
+
+// Markdown to PDF
+const pdf2 = await client.markdown('# Hello\n\nThis is **bold**.');
+fs.writeFileSync('doc.pdf', pdf2);
+
+// URL to PDF
+const pdf3 = await client.url('https://example.com');
+fs.writeFileSync('page.pdf', pdf3);
+```
+
+## API
+
+### `new DocFast(apiKey, options?)`
+
+| Parameter | Type | Description |
+|-----------|------|-------------|
+| `apiKey` | `string` | Your DocFast API key |
+| `options.baseUrl` | `string` | API base URL (default: `https://docfast.dev`) |
+
+### `client.html(html, options?)`
+
+Convert an HTML string to PDF. Returns `Promise<Buffer>`.
+
+### `client.markdown(markdown, options?)`
+
+Convert a Markdown string to PDF. Returns `Promise<Buffer>`.
+
+### `client.url(url, options?)`
+
+Convert a webpage URL to PDF. Returns `Promise<Buffer>`.
+
+### `client.templates()`
+
+List available templates. Returns `Promise<Template[]>`.
+
+### `client.renderTemplate(id, data, options?)`
+
+Render a template with data. Returns `Promise<Buffer>`.
+
+### PDF Options
+
+All conversion methods accept an optional `options` object:
+
+```typescript
+{
+  format: 'A4' | 'Letter' | 'Legal' | 'A3' | 'A5' | 'Tabloid',
+  landscape: boolean,
+  margin: { top: '20mm', bottom: '20mm', left: '15mm', right: '15mm' },
+  header: { content: '<div>Header HTML</div>', height: '30mm' },
+  footer: { content: '<div>Footer HTML</div>', height: '20mm' },
+  scale: 1.0,
+  printBackground: true,
+}
+```
+
+## Error Handling
+
+```typescript
+import DocFast, { DocFastError } from 'docfast';
+
+try {
+  const pdf = await client.html('<h1>Test</h1>');
+} catch (err) {
+  if (err instanceof DocFastError) {
+    console.error(err.message);  // "Invalid API key"
+    console.error(err.status);   // 403
+  }
+}
+```
+
+## License
+
+MIT