Sub-agents of non-admin profiles replaced the parent system prompt with
their own worker prompt, so the "one directory, no network, no secrets"
rules never reached them. build_subagent_system_prompt now appends a
[Boundaries] block for every non-admin profile, whatever prompt was
chosen.

Align the profile prompts with the actual tool surface alongside it:
allow 3D sub-agents to draft geometry but not publish or decide, publish
a preview PNG with the STL in both 3D profiles, document the assistant's
remaining tools, canonicalise MCP names, and fix the developer/navi_code
spawn ending, the server_admin field list, the discuss memory_search
guidance, and the navi-3d/navi-web/gnexus-book instructions.