Vane with external SearXNG incorrectly reports "Found 0 results" in Speed/Balanced

Vane with external SearXNG incorrectly reports "Found 0 results" in Speed/Balanced, even though SearXNG returns non-empty results.

Repro:

• Vane slim-latest
• external SearXNG via SEARXNG_API_URL
• same query works in Quality
• Speed/Balanced show Found 0 results

Direct call from inside the Vane container: curl -s "http://<searxng>/search?q=WTA%20500%20Stuttgart%20prize%20money%20table%202024%202025%202026&format=json"

Returned payload contains:

• "number_of_results": 0
• non-empty "results": [...]

So Vane seems to treat number_of_results as authoritative and discards valid results. This matches current SearXNG behavior where number_of_results can be obsolete/inaccurate while results still contains items.