## Summary

Deprecates `@railway/mcp-server` as a standalone MCP server and turns
the package into a final compatibility shim for the Railway CLI-bundled
MCP server.

The package no longer contains the TypeScript MCP implementation.
Existing `npx -y @railway/mcp-server` configs now delegate to:

```bash
railway mcp
```

## Changes

- Replace the standalone MCP server with a root `index.js` shim.
- Bump package version to `0.1.12`.
- Remove old source, tests, TypeScript build tooling, lockfile,
`server.json`, and editor config.
- Remove runtime and dev dependencies from `package.json`.
- Replace README with deprecation and migration guidance.
- Update checks to validate syntax and package contents.
- Update the release workflow to publish the final compatibility package
and deprecate the MCP Registry entry instead of publishing active
registry metadata.
- Add RFC for the package deprecation plan.

## Verification

- `npm test`
- `npm run build`
- `npm pack --dry-run`
- `env PATH=/nope node index.js`
- `node index.js --help`

## Follow-up

After the final package is published, an authenticated npm maintainer
should run:

```bash
npm deprecate "@railway/mcp-server" "Deprecated: Railway MCP is now bundled into the Railway CLI. Use 'railway mcp' or run 'railway mcp install'. See https://docs.railway.com/cli/mcp."
```