v0.1.27

A small feature release: proactive surfacing can now be scoped per upstream.

UpstreamServerConfig.surfacing_enabled — toggled with mms surfacing <server> [on|off] and shown in mms status — opts an upstream's tool responses in or out of the SURFACE stage from the shared stm_proxy.json, so every MCP client proxying through the same mms sees one consistent scope. Disabling skips surfacing (and the LTM search) for that upstream before the engine runs. Enforced in ProxyManager (reads the hot-reloaded config), not the SurfacingEngine gate.

See CHANGELOG.md [0.1.27]. Implemented in #422; released via #423.