muster release v5.37.4

filter_tools names the servers a sign-in would unlock. An agent that discovers tools with filter_tools — where muster’s own list_tools description and the platform’s agent prompts steer it — never learned that a Connector exists until the person had signed in to it: for a server the session is not connected to, the filter returned no tool and no hint, the agent answered “I have no Slack tool”, and the gateway’s Connect button, rendered from a core_auth_login result, never appeared; only list_tools reported servers_requiring_auth. filter_tools now carries servers_requiring_auth too, in list_tools’ shape (name, status, auth_tool, tool_prefix, family), narrowed to the servers whose tools the pattern could match once they are listed: every pending server without a pattern or under *slack*, slack alone under x_slack_*, none under core_* (so list_core_tools is unchanged). The toolset does not narrow it — toolset_requiring_auth still names the part of the toolset a sign-in would unlock — nor do query, description_filter and labels, which have no text to match before the sign-in; the list is sorted by name, as list_tools’ now is. An empty catalogue with such a server answers the structured page instead of No tools available to filter. The tool’s description says so, and the muster CLI’s filter listing prints the servers as its tool listing does. (#1351)