All RegisterTools and internal register*Tool methods updated from
*mcp.Server to *coremcp.Service. Tool registration calls updated to
use svc.Server() for SDK AddTool calls. Monitor subsystem updated
to store *coremcp.Service and access Server() for Sessions/ResourceUpdated.
Tests updated to create coremcp.Service via New() instead of raw SDK server.
Co-Authored-By: Virgil <virgil@lethean.io>
