feat: add yaml-ls plugin for YAML code intelligence v1.0.0

[vnz]

Summary

• Add new yaml-ls plugin providing YAML language server integration (go-to-definition, find-references, hover, diagnostics) for .yaml and .yml files
• Pure LSP plugin — no skills, hooks, or custom CLAUDE.md; uses yaml-language-server --stdio
• Register in marketplace and update root README

Test plan

• Install plugin: /plugin install yaml-ls@cc-plugins-vnz
• Verify yaml-language-server is detected: which yaml-language-server
• Open a .yaml file and confirm LSP features (hover, diagnostics) work
• Run prek run --all-files — all checks pass

🤖 Generated with Claude Code

[gemini-code-assist]

Code Review

This pull request introduces the yaml-ls plugin, which integrates the YAML language server to provide code intelligence features such as go-to-definition, find-references, and hover documentation. The changes include adding the plugin to the marketplace registry, defining its LSP configuration, and providing comprehensive documentation. Review feedback suggests updating the plugin descriptions in both the marketplace and plugin metadata files to explicitly include 'diagnostics' for better accuracy and consistency with other language server plugins.

[gemini-code-assist]

The description is missing diagnostics, which is a key feature of this language server and is mentioned in the README. For better accuracy and consistency with other LSP plugins in this marketplace (like terraform-ls), I suggest updating the description to include it.

Suggested change

	"description": "YAML language server (yaml-language-server) for code intelligence, go-to-definition, find-references, and hover docs",
	"description": "YAML language server (yaml-language-server) for code intelligence, go-to-definition, find-references, hover, and diagnostics",

[gemini-code-assist]

The description is missing diagnostics, which is a key feature of this language server and is mentioned in the plugin's README. For better accuracy and consistency, I suggest updating the description to include it.

Suggested change

	"description": "YAML language server (yaml-language-server) for code intelligence, go-to-definition, find-references, and hover docs in YAML files (.yaml, .yml)",
	"description": "YAML language server (yaml-language-server) for code intelligence, go-to-definition, find-references, hover, and diagnostics in YAML files (.yaml, .yml)",