[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/profile-followers.ts

@@ -6,7 +6,7 @@ import {
   useInfiniteQuery,
 } from '@tanstack/react-query'
 
-import {getAgent} from '#/state/session'
+import {useAgent} from '#/state/session'
 
 const PAGE_SIZE = 30
 type RQPageParam = string | undefined
@@ -15,6 +15,7 @@ const RQKEY_ROOT = 'profile-followers'
 export const RQKEY = (did: string) => [RQKEY_ROOT, did]
 
 export function useProfileFollowersQuery(did: string | undefined) {
+  const {getAgent} = useAgent()
   return useInfiniteQuery<
     AppBskyGraphGetFollowers.OutputSchema,
     Error,