refactor(skills): update dspy-ruby skill to DSPy.rb v0.34.3 API (#162)

Rewrite all reference files, asset templates, and SKILL.md to use
current API patterns (.call(), result.field, T::Enum classes,
Tools::Base). Add two new reference files (toolsets, observability)
covering tools DSL, event system, and Langfuse integration.

🤖 Generated with [Claude Code](https://claude.com/claude-code)

Co-authored-by: Claude Opus 4.6 <noreply@anthropic.com>

plugins/compound-engineering/.claude-plugin/plugin.json

@@ -1,6 +1,6 @@
 {
   "name": "compound-engineering",
-  "version": "2.31.0",
+  "version": "2.31.1",
   "description": "AI-powered development tools. 29 agents, 24 commands, 18 skills, 1 MCP server for code review, research, design, and workflow automation.",
   "author": {
     "name": "Kieran Klaassen",