Add MCP server to AST tool

Integrates the MCP server functionality into the AST tool binary. This
allows the tool to act as a server for LLM integration, enabling
communication over stdio. The server can list available bindings and
execute scripts.

src/ast/mod.rs

@@ -3,6 +3,7 @@ pub mod compiler;
 pub mod diagnostics;
 pub mod environment;
 pub mod lexer;
+pub mod mcp_server;
 pub mod nodes;
 pub mod parser;
 pub mod rtl;