In src/everything:
* Refactor / move streamableHttp.ts, sse.ts, and stdio.ts to transports/
* Move everything.ts to server/ for reference
* Add server/index.js
- exports the createServer function
- import registerTools from tools/index.js
- in createServer()
- read instructions.md and include in ServerOptions for McpServer constructor
- construct McpServer instead of Server
- call registerTools, passing server
* Add tools/echo.ts
- define EchoSchema
- define tool config
- export addToolEcho function
- in addToolEcho()
- register handler for Echo tool
* Add tools/index.ts
- import addToolEcho
- export registerTools function
- in registerTools()
- call addToolEcho
