Add simple-lang development skill

[ormastes]

Summary

Adds a development skill for the Simple Language compiler and toolchain.

• 68 MCP tools for code intelligence, debugging, build, test, VCS, and analysis
• Native binary MCP server via npm: @simple-lang/mcp-server
• Also published on MCP Registry: io.github.ormastes/simple-mcp-server

Setup

npx @simple-lang/mcp-server

Or in .codex/config.toml:

[mcp.simple-mcp]
command = "npx"
args = ["-y", "@simple-lang/mcp-server"]