Fix the "HTTP with SSE" example

[cliffhall]

In README.md

• Fix the HTTP with SSE example.
• Declare transport outside of the /sse handler so it can be seen inside the /messages handler

Fixes #187

Motivation and Context

The HTTP with SSE example doesn't work because the transport is declared as a const inside the handler for /sse endpoint and referenced in the handler for the /messages endpoint.

Discovered this while researching #187

Typechecking as it is currently written gives the following message:

You can build it and it will run, but when you attempt a connection, you will get

  await transport.handlePostMessage(req, res);
  ^

ReferenceError: transport is not defined

How Has This Been Tested?

Ran the example with the changes and connected successfully with the Inspector

Breaking Changes

Nope.

Types of changes

• Bug fix (non-breaking change which fixes an issue)
• New feature (non-breaking change which adds functionality)
• Breaking change (fix or feature that would cause existing functionality to change)
• Documentation update

Checklist

• I have read the MCP Documentation
• My code follows the repository's style guidelines
• New and existing tests pass locally
• I have added appropriate error handling
• I have added or updated documentation as needed

Additional context

[cliffhall]

This PR has been superseded by #197. Closing.