feat: add bpmnlint integration for BPMN diagrams

[alibama]

my sincere apologies for any dumb stuff. my engagement in this process is pitiful, and claude is 1000% doing most of the work, so, ya know... i'm glad to do additional testing of course, and anything else that would be of assistance

Surface model validation issues directly in rendered diagrams and in the editor via bpmn-js-bpmnlint. A toggle button on the canvas shows clickable error/warning overlays on the offending elements.

• New lint attribute on : on | off | inactive. The viewer defaults to button-present-inactive; the editor defaults to active.
• Rules live in .bpmnlintrc (extends bpmnlint:recommended) and are packed into the committed bundles at build time via bpmnlint-pack-config, since bpmnlint cannot resolve rules in the browser. build:vendor handles this automatically.
• The lint module runs in a plain Viewer (every injected service is present; editorActions resolves optionally), so no viewer upgrade was needed.
• Add syntax tests for the lint attribute; default output is unchanged when the attribute is absent.

Refs #83

[jdehaan]

No worries, really thanks for sharing this PoC.

[jdehaan]

I think the changes are all basically quite good. I just have a technical issue. I enforced signed commits here. I propose I will open yet another PR with your commit (rebased) and add another commit with my own additions so you can tell me if you're ok with that for your use case. Then I think it is something nice to get merged!

-> Ref #87

Sorry for the mess I thought it would work with keeping this one. I think next time I can cherry pick the commits you indicate to me from your forked repos. Then you have no hassle with the handling.

You can have a look at each of the commits here: https://github.com/Color-Of-Code/dokuwiki-plugin-bpmnio/pull/87/commits (the first is the rebased you authored and the second my additional changes)

[jdehaan]

Closed in favor of #87 (as agreed above)