[Session] Add useAgent hook and replace (#3706)

* Hook it up

* Memoize getAgent method

* Use one shared reference

---------

Co-authored-by: Dan Abramov <dan.abramov@gmail.com>

src/state/queries/actor-search.ts

@@ -2,7 +2,7 @@ import {AppBskyActorDefs} from '@atproto/api'
 import {QueryClient, useQuery} from '@tanstack/react-query'
 
 import {STALE} from '#/state/queries'
-import {getAgent} from '#/state/session'
+import {useAgent} from '#/state/session'
 
 const RQKEY_ROOT = 'actor-search'
 export const RQKEY = (query: string) => [RQKEY_ROOT, query]
@@ -14,6 +14,7 @@ export function useActorSearch({
   query: string
   enabled?: boolean
 }) {
+  const {getAgent} = useAgent()
   return useQuery<AppBskyActorDefs.ProfileView[]>({
     staleTime: STALE.MINUTES.ONE,
     queryKey: RQKEY(query || ''),