Use roots cache in get-roots-list tool

* In get-roots-list.ts, query the server's cache of the latest roots from the client and only request the list from the client if it doesn't exist.
* In roots.ts, export the roots map

src/everything/server/roots.ts

@@ -5,7 +5,7 @@ import {
 } from "@modelcontextprotocol/sdk/types.js";
 
 // Track roots by session id
-const roots: Map<string | undefined, Root[]> = new Map<
+export const roots: Map<string | undefined, Root[]> = new Map<
   string | undefined,
   Root[]
 >();