PoC: adds stdio-to-sse proxy

[epps]

To test the proxy, simple run the following FastMCP server in a virtual env:

from mcp.server.fastmcp import FastMCP

mcp = FastMCP("Demo")


@mcp.tool()
def add(a: int, b: int) -> int:
    """Add two numbers"""
    return a + b


if __name__ == "__main__":
    mcp.run(transport="sse")

When running, you should be able to see the the SSE even endpoint at http://localhost:8000/sse in your browser.

Stepping through the integration test should provide a good overview of how the proxy functions.

To run the inspector and test tool listing and usage, in your terminal run:

npx @modelcontextprotocol/inspector go run main.go http://localhost:8000/sse proxy-logs.txt

All you have to do is click "Connect" in the inspector UI.

[epps]

Closing PoC PR in favor of improved proxy implementation.