fix: refine community cloud search results

[imantsk]

Summary

Community Cloud search returned no results for any query (e.g. "woo", "javascript"). Two bugs in Cloud_API::fetch_search_results:

1. Empty results even when the API responded. The refactored unpack_request_json() returns $json['data'] (a bare list), but Cloud_Snippets expects the full response envelope (it reads data/snippets, meta, available_filters). So results normalised to an empty set with total_snippets: 0. get_featured_snippets() passes the full $json and worked — search did not. Fix: pass the full decoded envelope, matching featured (and the 3.9.x behaviour).
2. Cold-cache timeouts. wp_remote_get used WordPress's 5s default; the cloud search endpoint can take longer on a cold cache, so the request failed with cURL error 28 → empty. Fix: a 15s timeout for the search request.

Verification

Against production codesnippets.cloud: "woo" → 338 results, "javascript" → 12 (was 0/0). Confirmed the request URL/params were already correct and that the cloud API itself returns the expected data — the fault was entirely client-side parsing + timeout.

Notes

• Stacked on fix: WordPress 7.0 admin UI compatibility #401 (branched from fix/wp7-admin-ui-compat); the diff here is the single Cloud_API change. Can be rebased onto core-beta to stand alone if preferred.
• The slow cold-cache search is also being addressed server-side (cloud-app: fulltext-index fix), which removes the need for the long timeout over time.