docs(modeling/tools): add kUML — Kotlin DSL for UML, SysML 2 and C4

[betschwa]

What

Adds kUML — kuml-dev/kUML — to docs/modeling/tools.md, alongside Diagrams.net, Visual Paradigm, LucidChart, Excalidraw etc.

Why it fits this list

kUML is a Kotlin-based diagrams-as-code toolchain for UML, SysML 2 and C4 — a strong fit for the Modeling → Tools category. It treats architectural diagrams as version-controlled source code rather than artefacts of GUI tools.

Highlights

• DSL: Kotlin script (.kuml.kts) for UML class/component/sequence/state-machine, SysML 2 (BDD/IBD/STM), and C4 (Context/Container/Component) diagrams.
• Renderers: SVG and PNG, content-aware sizing, ELK-Bridge layout plugin.
• Distribution: CLI (Homebrew tap, SDKMAN!, direct download, jpackage DMG/MSI/DEB/RPM), Compose Desktop app, IntelliJ-platform plugin, Obsidian community plugin, Asciidoctor extension on Maven Central ([kuml] block macro).
• Interop: XMI import/export (Eclipse UML2), Structurizr DSL migration, Java/Kotlin reverse engineering (kuml reverse).
• Plugin SPI: stable extension points for themes, renderers, layout engines, codegen, reverse engineering — signed plugin registry.
• AI Assistant: optional Koog-based assistant in the desktop app (multi-LLM, sandboxed patch-apply).
• License: Apache-2.0.

Format

Followed the convention from contributing.md (LINK | GitHub-User/Repo - DESCRIPTION) and the existing style of neighbouring files. Appended at the end of docs/modeling/tools.md.

Checklist

• One file changed, one category
• Concise, descriptive entry
• Project is open source (Apache-2.0) and actively developed
• Public website + GitHub repo + Maven Central artefacts