Use Perplexity for Nous-managed search, retaining Firecrawl for extract
and as a per-call search fallback. Explicit search overrides and direct
keys keep their own billing paths; fallback results are never cached.
When the managed route is selected but the Tool Gateway is unavailable
(unentitled account or no Nous token), search reports that selection
error instead of asking for a direct key the user never chose.
The managed search vendor is unannounced, so user-facing copy names the
capability rather than the vendor: status, portal and docs say "managed
web search", and the fallback annotation reads `managed_primary`. Direct-key
configuration docs are unchanged.
Routing, auth, payload, cache and entitlement regressions are covered
through real config loading and local HTTP.
Follow-up to the cherry-picked gateway fix: instead of re-inferring "keyless
mode" from the key env var (wrong for Firecrawl, whose managed-gateway and
self-hosted routes bypass the ring without a key), `_rescue_eligible` asks the
ring vendor's own predicate — `_use_keyless_ring()` for Firecrawl, `use_keyless`
for the others. That covers the persisted `nous` selection the contributor fix
handled AND the legacy never-configured fallback onto a ready gateway, plus
`FIRECRAWL_API_URL`. A ring vendor that actually walked the ring stays
ineligible (its failure means the ring already failed). Docs mention the
gateway route is rescued.
