sse server does not process endpoint correctly

[shendaxia-sm]

Describe the bug

mcp sse server does not remove last path when join endpoint url.
for example: baseUrl is http://localhost/sse, and server return sse data:

event:endpoint data:mesages?sessionId=a7f13c57-3ebe-4676-8079-bab962990583

sdk return endpoint http://localhost/sse/mesages?sessionId=a7f13c57-3ebe-4676-8079-bab962990583

the correct endpoint should be http://localhost/mesages?sessionId=a7f13c57-3ebe-4676-8079-bab962990583

python-sdk can correctly return the endpoint

A clear and concise description of what the bug is.

To Reproduce
Steps to reproduce the behavior:

embeddedServer(CIO, host = "127.0.0.1", port = port) {
    install(SSE)
    routing {
        sse("/sse") {
            val transport = SSEServerTransport("message", this)
            val server = configureServer()

            // For SSE, you can also add prompts/tools/resources if needed:
            // server.addTool(...), server.addPrompt(...), server.addResource(...)

            servers[transport.sessionId] = server

            server.onCloseCallback = {
                println("Server closed")
                servers.remove(transport.sessionId)
            }

            server.connect(transport)
        }
        post("/message") {
            println("Received Message")
            val sessionId: String = call.request.queryParameters["sessionId"]!!
            val transport = servers[sessionId]?.transport as? SSEServerTransport
            if (transport == null) {
                call.respond(HttpStatusCode.NotFound, "Session not found")
                return@post
            }

            transport.handlePostMessage(call)
        }
    }
}.start(wait = true)

Expected behavior
A clear and concise description of what you expected to happen.

Logs
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Additional context
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