[Server] (Re-)Implement Http/SSE-based Transport

[chr-hertel]

The original php-mcp/server component already had a Http/SSE-based Transport and same for Symfony's MCP SDK with its SSE Stream Transport.

Goal of this issue is to bring in a new Http/SSE-based Transport implementation, that is compatible with this SDK's architecture.

---

Please announce yourself before working on this - so we can avoid duplicate effort.

[macoaure]

I'm working on it, can you assign it to me?

[chr-hertel]

Hi @macoaure, we're closing this one - the transport is deprecated and with #49 we're good for HTTP.