Add claude-agent-sdk-ruby to SDKs & Development Kits

[ya-luotao]

Adds claude-agent-sdk-ruby to SDKs & Development Kits, placed by star count like the neighbouring entries.

• Repo: https://github.com/ya-luotao/claude-agent-sdk-ruby (MIT, active, CI on Ruby 3.2–3.4)
• Unofficial Ruby port of the Claude Agent SDK; same CLI wire protocol as the official Python/TypeScript SDKs
• Notable: in-process MCP tools, all 27 hook events, Rails integration, built-in OpenTelemetry/Langfuse observer, pinned-CLI vendoring for hermetic deploys