Merge remote-tracking branch 'origin/master' into gitea/feature/end

Resolved conflicts taking origin/master (v0.5.55) as canonical, with local
features re-applied:
- runtime log level (LOG_LEVEL env + dashboard Settings → Logging, applied
  immediately and persisted across restarts)
- free/noAuth provider enable/disable toggle via providerStrategies.enabled
- parallel model testing (Test All Models / Test Selected Keys)

open-sse/handlers/search/normalizers.js

@@ -1,7 +1,6 @@
 /**
  * Search Response Normalizers
  *
- * Ported from OmniRoute open-sse/handlers/search.ts.
  * Each normalizer maps a provider-specific response into the unified SearchResult shape.
  */