Align tests and examples with reference implementation

Port tests and examples from the reference SDK implementation
(modelcontextprotocol/typescript-sdk#1399)
to the extension wrapper, adapted for GroupingExtension/GroupingClient.

Tests mirror the reference's 3 server tests + 2 notification tests.
Server example aligns tool schemas, resource URIs, and content.
Client example adds depth control, cycle-safe traversal, and
multi-group filtering.

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

Author: chughtapan