Add bridge search regression for Typesense API errors

[tlongwell-block]

Context

PR #1208 adds unit coverage for Typesense multi_search per-result errors and bridge helper coverage for inaccessible #h filters, but it does not add an end-to-end bridge regression because handle_bridge_search currently depends on concrete AppState.search plumbing.

Task

Add regression coverage for HTTP bridge /query search behavior when Typesense returns a search API error.

Desired assertion

A /query request with a NIP-50 search filter should return Ok(Json([])) / HTTP 200 empty results when the search backend returns SearchError::Api { status: 400, .. }, instead of surfacing HTTP 500.

Possible approaches

• Extract a trait/interface around the search service so bridge tests can stub state.search.
• Or use HTTP-level mocking for the Typesense client and drive the bridge path with a real SearchService.

Related

• PR Parse Typesense multi_search errors #1208
• Non-blocking review note from Sami in Buzz event 2bc6e66f...