Connect gnexus-book MCP server and enable in profiles ...

- mcp_servers.json: SSE transport to 192.168.1.170:8001
- server_admin profile: all 16 gnexus-book tools
- discuss profile: read-only gnexus-book tools (docs + inventory)

Co-Authored-By: Claude Opus 4.7 <noreply@anthropic.com>