Expose server tool annotations on MCP::Client::Tool

[rickreyhsig-wealthbox]

Fixes#446

Summary

Client#tools / Client#list_tools silently drop the server's annotations
field when building MCP::Client::Tool objects, even though the server sends
it in every tools/list response (Tool#as_json includes
annotations: annotations_value&.to_h). Callers have no way to read a tool's
readOnlyHint / destructiveHint / title / etc. from the client side today
— they have to bypass the public API and re-page tools/list via the private
#request method just to get at the raw definition.

Change

• MCP::Client::Tool gains an annotations reader, populated the same way as
  the existing output_schema (optional kwarg, raw hash passed through as
  received on the wire — no reshaping into MCP::Tool::Annotations, since
  that class's constructor expects snake_case keys and the wire format is
  camelCase).
• Client#list_tools passes annotations: tool["annotations"] through when
  constructing each Tool.

Test plan

• Added/updated unit tests in test/mcp/client/tool_test.rb and
  test/mcp/client_test.rb covering: annotations present, annotations absent
  (nil), and the full-parameters constructor case.
• bundle exec rake test — 1270 runs, 0 failures.
• bundle exec rubocop — no offenses on changed files.

[koic]

@rickreyhsig-wealthbox This looks good to me. Since I'll merge this after the v1.0 release (#470), could you remove the change entry to the CHANGELOG.md file that are currently causing the merge conflict? I can update the CHANGELOG.md as part of the release process.

[rickreyhsig-wealthbox]

@rickreyhsig-wealthbox This looks good to me. Since I'll merge this after the v1.0 release (#470), could you remove the change entry to the CHANGELOG.md file that are currently causing the merge conflict? I can update the CHANGELOG.md as part of the release process.

@koic I've removed the entry

[koic]

@rickreyhsig-wealthbox Could you squash your commits into one?

[rickreyhsig-wealthbox]

@rickreyhsig-wealthbox Could you squash your commits into one?

@koic done!

[koic]

Thanks!