mountMcp

Mount an McpServer onto a vibe.d URLRouter at the configured path, implementing the modern Streamable HTTP transport (single endpoint): - POST: a JSON-RPC message/batch; returns application/json for requests, or 202 Accepted with no body when the payload needs no reply. - GET: on the stable revisions, opens a standalone server->client SSE stream wired to the server-push channel (McpServer.notify); on the draft, which drops the standalone stream, GET -> 405. - DELETE: the draft has no protocol-level sessions to tear down -> 405.