feat(extract): remove the autoparse fallback and add domain preparation

[jonathan-zenrows]

What changes for callers

extract() and extract_async() no longer retry with autoparse. A 403 with code: "REQS007" and the legacy 402 with code: "AUTH010" come back to the caller as is, in one request. The automatic retry hid the prepare step and charged for an autoparse call that often returned unusable data. Autoparse is deprecated.

fallback_to_autoparse stays in both signatures, so existing calls keep working, but it is deprecated and has no effect. Passing True emits a DeprecationWarning that points at prepare_domain().

A 403 REQS007 problem body can now carry a reason. Check it when present; older responses may not carry it:

• domain_not_prepared: prepare the domain with client.prepare_domain(), poll client.prepared_domain_status() until status is "ready", then retry.
• page_not_recognised: the domain is served, but this page isn't one Extract extracts (a home, search, login or category page). Try a product, article or listing page, or retry once in a few minutes. Preparing again changes nothing.
• domain_not_enabled: preparing doesn't help. Use css_extractor, or contact support.

response = client.extract(url)
if response.status_code == 403 and response.json().get("code") == "REQS007":
    reason = response.json().get("reason")  # None on older responses

New: prepare_domain(domain, example_urls) and prepared_domain_status(domain) (plus _async versions) call POST /v1/extract/prepared-domains and GET /v1/extract/prepared-domains/{domain} and return the parsed status. Errors raise PreparedDomainError.

Details

• The fallback code path is deleted; no option re-enables it.
• prepare_domain() / prepared_domain_status() send the key in X-API-Key, never poll, and skip the client's retries adapter, so a 429 or 503 comes back on the first answer. An empty or whitespace-only domain raises ValueError before any request. PreparedDomainError carries status_code, code, detail, reason, retry_after and the whole problem body.
• The README and docstrings describe the three reason cases and mark the autoparse fetch parameter as deprecated.

This ships as feat commits (minor version) through release-please.

Tests

• REQS007 and AUTH010 are returned as is, in one request, with and without fallback_to_autoparse=True (sync and async); passing True emits a DeprecationWarning attributed to the caller.
• The reason is readable from the response body.
• The prepare-domain methods against a stubbed HTTP server: request shape and auth header, parsed status, domain escaping, empty domains, no polling, no retries with retries=1, every documented error answer.

make check (ty, ruff check, ruff format --check), make test (256 passed) and the generated-models check pass locally. A production smoke test returned 403 REQS007 in one request with defaults and with fallback_to_autoparse=True, plus the warning.