fix: update text_search endpoint to search v2 API (#496)

[arybhatt4533]

Description

This PR fixes issue #496 where text_search was returning a 503 Server Error due to the deprecation/blocking of unauthenticated GET requests on the old /cgi/search.pl endpoint.

The endpoint has been updated to use the new Search V2 API (/api/v2/search), restoring functionality for text-based product searches.

Changes Made

• Updated text_search endpoint in src/openfoodfacts/api.py from /cgi/search.pl to /api/v2/search.
• Removed redundant json=1 parameter as V2 returns JSON by default.
• Updated corresponding unit tests in tests/unit/test_api.py to match the new endpoint URL.

How Has This Been Tested?

• Ran unit tests via pytest:

  python -m pytest tests/unit/test_api.py

@hangy

[humanifest-bot]

Verification note for the existing #496 discussion, using OpenAI Codex (GPT-6, agentic verification).

I checked PR head 970a7290a8a5869de8f5784324c166212fdd15ca: all 38 unchanged SDK API tests pass locally. There is still a search-contract concern:

• The official v2 search documentation says full-text requests are unsupported.
• The pinned server filter explicitly removes search_terms before query construction.
• Four cases executing that original filter forward identical empty filters for ordinary text, a distinct nonsense term and no text; a structured-brand control survives. Pagination and sorting controls also survive.

This is a source/function verification, not a live API or full-server result. The SDK's fixed response mocks establish request/response handling but cannot establish query-dependent product matching.

Reproduction scripts, exact revisions and coverage limits are available. Sharing this to support your existing work before the URL substitution is treated as restoring text-search semantics. The intended authentication/full-text contract still needs maintainer confirmation; no replacement PR or independent human review is claimed.

[sonarqubecloud]

Quality Gate passed

Issues
0 New issues
0 Accepted issues

Measures
0 Security Hotspots
0.0% Coverage on New Code
0.0% Duplication on New Code

See analysis details on SonarQube Cloud

[arybhatt4533]

Thanks for the detailed verification! Yes, the endpoint URL swap restores request handling and prevents the 503 error, but as noted, Search V2's handling of raw search_terms depends on the ongoing server-side API v2 search contract updates. I've updated the branch with develop and am waiting for maintainer input (@teolemon / @hangy) on whether we should merge this endpoint update now or pair it with additional parameter mappings for V2

[TaciteOFF]

The updated tests use fixed responses, so they cannot show whether the API actually uses the search words?