Support the 2026-07-28 MCP protocol revision (follow-up to #2433) #2728

Tracking issue split out of #2433 (closed by #2556).

#2556 made the server/discover connect probe log at level=info and kept the -32601 Method not found reply, so current MCP clients fall back to initialize as before. That fixed the noisy log the report was about. It deliberately did not add support for the 2026-07-28 MCP protocol revision itself.

This issue tracks the question of whether and how to support that revision, for example answering server/discover and negotiating the newer version where a client asks for it, while staying compatible with clients on the 2025-11-25 revision.

Background and the versioning analysis are in #2433 (thanks to @xxww0098 for the report and @Zhuoxi2000 for reading the 2026-07-28 rules against the code). No decision has been made yet.