Remove SearXNG search backend, use Firecrawl exclusively

SearXNG was a fallback search backend that added complexity without
being used in practice. All search-dependent features (web search,
government DB checks, vetting orchestrator, tracker mapping) now use
Firecrawl exclusively. Removes the SEARCH_ENDPOINT config plumbing
from probodconfig, bootstrap, Helm charts, and all callers.

Signed-off-by: Émile Ré <emile@probo.com>

pkg/probod/tracker_mapping.go

@@ -49,7 +49,6 @@ func (impl *Implm) buildTrackerMappingConfig(
 	return cookiebanner.TrackerMappingConfig{
 		LLMClient:         llmClient,
 		Model:             agentCfg.ModelName,
-		SearchEndpoint:    impl.cfg.SearchEndpoint,
 		FirecrawlEndpoint: impl.cfg.Firecrawl.Endpoint,
 		FirecrawlAPIKey:   impl.cfg.Firecrawl.APIKey,
 	}, nil