Deploy: add nginx, systemd services, scripts, MCP info endpoint ...

- nginx reverse proxy on port 80 for UI + /api/ + /mcp/
- systemd user services: backend (8000), MCP SSE (8001)
- install.sh and deploy.sh for automated setup
- /mcp/info endpoint to expose MCP instructions and tools list
- MCP server instructions expanded for AI agent workflows
- Update server README with deployment docs

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

merge

Document proactive MCP usage for agents

Add Gnexus Book MCP server

Add broad knowledge inventory types

Document public VPN and internal proxy route

Add inventory relationship graph API

Add validation guardrails for agent-maintained docs

Add documentation foundation and backend maintenance API