feat: add `--dump assets` to enumerate page sub-resources
Adds a `--dump assets` flag to output all page-referenced sub-resources
(scripts, stylesheets, images, iframes, media, embeds, objects) as NDJSON,
allowing users to easily replay the asset graph.
- Output format: `{"url":"https://example.test/app.js","type":"script"}`
- URLs are resolved against the page origin (matching `--dump links`).
- The `type` tag is derived from the source element. `<link>` elements map
their `rel` attribute to specific types (stylesheet, icon, manifest, preload,
prefetch, modulepreload, dns-prefetch, preconnect, alternate), falling back
to "link" if missing or unknown.
- Adds 7 tests covering URL resolution, rel-mapping, supported selectors,
and empty-attribute skipping.
- Updates README dump-format table and examples.
Ben Younes
3d12f76d8e