muster release v5.16.1

filter_tools echoes a header-declared toolset (#1194). The response’s toolset field names the toolset the returned tools were resolved within: the toolset argument when one is given, else the request’s X-Muster-Toolset – as declared, e.g. ["preset:read-only"]. Before, only the argument was echoed: an agent whose toolset the platform sets by header got total/filtered_count scoped and toolset_unmatched filled but no toolset, so it had no way to learn which toolset bounds it short of a refused call_tool, and a transcript did not show which toolset a discovery call ran under. With both header and argument the argument keeps winning (it resolves within the header’s toolset). presets stays behind include_presets or the argument, so a header-scoped discovery call does not grow. list_core_tools, which shares the engine, echoes the header the same way. Scenario: toolset-filter-tools-echo.