[Feature Request]: Add Kroki service for text-as-diagrams rendering

[theletterf]

Prerequisites

• I have searched existing issues to ensure this feature hasn't already been requested
• I have tested using the latest version of docs-builder

What problem are you trying to solve?

Experimental support for text-as-diagrams using Kroki was added in #1599, but it relies on the Kroki free services, lacks caching, and could be unreliable.

Proposed Solution

To go forward with Kroki as the provider of rendered diagrams, we should:

1. Deploy Kroki as a container using the yuzutech/kroki image in a private network
2. Add a reverse proxy with API key validation, rate limiting, CORS headers, and TLS
3. Modify the code to replace the hardcoded Kroki.io URL, with API key
4. (Optional) Add telemetry/logging for Kroki calls

Examples and Research

Docs: https://docs.kroki.io/kroki/setup/install/

Alternative Solutions

No response

Additional Context

No response

How important is this feature to you?

Important

[theletterf]

@Mpdreamz Opened this one to continue the conversation around diagrams.