Add dark mode support and Deck card dependencies

[ernestomgz]

Summary

This PR improves NCGantt’s visual integration with dark mode and adds support for rendering dependencies between Deck cards in the Gantt chart.

Changes include:

• Add CSS variables for light and dark Gantt colors
• Improve Gantt, popup, status, and settings styling in dark mode
• Invert bundled action icons when dark mode is active
• Re-render the Gantt chart when the system color scheme changes
• Parse Deck card links from card descriptions and use them as Frappe Gantt dependencies

Dependency Format

Dependencies are detected from Deck card URLs in the card description. For example, a description containing a link with card/123 creates a dependency on task card-123.

Testing

• Checked JavaScript syntax with node --check js/ncgantt_NCGantt.js
• Manually reviewed the diff against upstream/main

Screenshots

Dependency linking in a Deck card description:

Rendered dependency in the card description:

Dark mode with dependency arrow in the Gantt chart:

[niclasheinz]

Hey @ernestomgz

First of all, I apologise for the late reply!

In the meantime, the next major release, version 34.0.0, will include a Gantt chart view that is integrated directly into the Nextcloud Deck app.

For references, you can check out the PR: nextcloud/deck#7812