If there are many searches in the `$LOAD_PATH` in the user environment,
require will perform unnecessary searches that are not needed.
In contrast, `require_relative` is efficient because it uses a relative path.
- fix `lib/mcp-ruby` auto-import path
- implement server resources
- add basic listing of resources to Server
- allow setting handlers on Server
- wrap handler method results
- make tool definition more declarative
- make prompt definition more declarative
- bump dependency versions