Reuse applyGrokFreeMessagesFunctionToolCacheRoute on native /v1/responses
and the Grok WS HTTP bridge so Free OAuth requests with client function
tools get the same mixed-tools cache route as the Messages bridge
(append/convert web_search and x_search).
Also dedupe: Grok Build already declares function tools named web_search,
so naive append caused "Duplicate tool names: web_search". Convert those
function entries to native tool types and skip duplicates.
Only Free OAuth accounts (isKnownGrokFreeAccount); paid/unknown unchanged.
rurucxk
29e39b96e5