Expand architecture diagram coverage

[lraigosov]

Summary

• expand the Mermaid architecture diagram in README to cover the current service topology
• add the missing Ollama model services and their init containers
• document the split between bridge-based operational services and the shared red-principal network
• add architecture notes for Portainer, Open WebUI, and LibreChat relationships

Validation

• reviewed the diff between origin/main and origin/dev
• validated Mermaid syntax successfully
• confirmed Mermaid preview renders correctly from README

Impact

• documentation-only change
• no runtime or compose behavior changes

[Copilot]

Pull request overview

This PR updates the repository documentation by expanding the Mermaid “Arquitectura lógica” diagram in README.md to reflect the current Docker service topology, including the separation between operational (bridge) services and the shared red-principal network, and adding relationships for the Ollama model services and chat UIs.

Changes:

• Expanded the Mermaid architecture diagram to include clients, bridge-based operational services (Portainer/Agent + Docker socket), and the red-principal service mesh.
• Added the missing Ollama model services (qwen3-coder, qwen3) and their init containers, plus their relationships with Open WebUI and LibreChat.
• Added architecture notes clarifying the network split and how Open WebUI / LibreChat consume Ollama endpoints.

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