[Feature Request] Support for Streamable MCP

Currently filestash uses an SSE MCP, this seems to be outdated with many providers either dropping support for it or not properly supporting it at all due to it being legacy. Allowing Streamable HTTP MCP, this would be excellent as it would provide a far better experience and allow support for almost every major platform e.g. ChatGPT, Claude Openwebui (self hosted LLMs) etc.