Bootstrapping a ReScript MCP

[zth]

This takes the first steps towards bootstrapping a dedicated ReScript MCP, with a few initial commands.

Trying it out

Very very early so far, but if you want to play around with it in a local project, do this:

1. Clone and build this PR just like you'd normally build the compiler (check CONTRIBUTING.md if you don't know how)
2. Make sure you have Bun installed
3. Run yarn install in the mcp folder
4. For example using Cursor, add + adapt this to .cursor/mcp.json in your local project:

{
  "mcpServers": {
    "rescript-mcp": {
      "command": "bun",
      "args": ["/Users/zth/OSS/rescript-compiler/mcp/server.ts"]
    }
  }
}

Now you should get the MCP as an option in Cursor.

When you make changes to the MCP, reload it in Cursor (or reload the window of Cursor entirely).