Generic document support

[kepano]

• Allow defuddle/node to accept any DOM Document (linkedom, JSDOM, happy-dom, etc.) instead of requiring JSDOM. Callers choose their own DOM implementation.
• Fixed linkedom compatibility issues: replaced isConnected checks with parentNode (linkedom doesn't support isConnected on cloned documents), and added normalize() to merge fragmented text nodes from HTML entity parsing.
• Precompiled partial selector regex from PR Add Linkedom Node target #157 (@pedraal).
• Switch CLI and tests from JSDOM to linkedom.
• Tests can run against both DOM implementations: npm test (linkedom) and npm run test:jsdom.

Backward compatibility

Passing an HTML string or JSDOM instance to Defuddle() still works but is deprecated. Pass a Document instead:

// Before (deprecated)
await Defuddle(htmlString);
await Defuddle(jsdomInstance);

// After (linkedom)
import { parseHTML } from 'linkedom';
const { document } = parseHTML(htmlString);
await Defuddle(document, 'https://example.com/article');

// After (JSDOM)
import { JSDOM } from 'jsdom';
const dom = new JSDOM(htmlString, { url: 'https://example.com/article' });
await Defuddle(dom.window.document, 'https://example.com/article');