Add Ruby MCP Server Development collection (#330)

- Add Ruby MCP server best practices instruction
- Add Ruby MCP server project generator prompt
- Add Ruby MCP expert chat mode
- Add Ruby MCP development collection manifest
- Update category READMEs

Features:
- Server setup with official mcp gem
- Tool/prompt/resource handlers with classes
- Rails controller integration
- Stdio and HTTP transport support
- Input/output schemas with validation
- Tool annotations for behavior hints
- Structured content in responses
- Exception reporting and instrumentation
- Minitest test examples

Co-authored-by: Aaron Powell <me@aaron-powell.com>

collections/ruby-mcp-development.collection.yml

@@ -0,0 +1,35 @@
+id: ruby-mcp-development
+name: Ruby MCP Server Development
+description: 'Complete toolkit for building Model Context Protocol servers in Ruby using the official MCP Ruby SDK gem with Rails integration support.'
+tags: [ruby, mcp, model-context-protocol, server-development, sdk, rails, gem]
+items:
+  - path: instructions/ruby-mcp-server.instructions.md
+    kind: instruction
+  - path: prompts/ruby-mcp-server-generator.prompt.md
+    kind: prompt
+  - path: chatmodes/ruby-mcp-expert.chatmode.md
+    kind: chat-mode
+    usage: |
+      recommended
+
+      This chat mode provides expert guidance for building MCP servers in Ruby.
+
+      This chat mode is ideal for:
+      - Creating new MCP server projects with Ruby
+      - Implementing tools, prompts, and resources
+      - Setting up stdio or HTTP transports
+      - Debugging schema definitions and error handling
+      - Learning Ruby MCP best practices with the official SDK
+      - Integrating with Rails applications
+
+      To get the best results, consider:
+      - Using the instruction file to set context for Ruby MCP development
+      - Using the prompt to generate initial project structure
+      - Switching to the expert chat mode for detailed implementation help
+      - Specifying whether you need stdio or Rails integration
+      - Providing details about what tools or functionality you need
+      - Mentioning if you need authentication or server_context usage
+
+display:
+  ordering: manual
+  show_badge: true