[mrtfn]

Summary

Two fixes for the roadmap (Gantt chart) view:
There was an event propagation bug when clicking on the task preview window on the roadmap which prevented it from opening the task detail popup.
Also the arrow was misleading, since it was point the blocking task to the blocked task which is wrong! The blocker comes first and the arrow should start from its right end edge of the rectangle and leads to the most right edge of blocked task.
Also there were another case that when you move a blocked task way behind in the timeline(before the blocker task) the arrow would switch the side of the rectangle which changes the whole meaning of the depends on relation. and that fixed too.

It has quite some other problems which ill try to address when i have the time, its important for me because i use Gannt charts alot.

1. Dependency arrows render reliably — Fixed arrow positioning logic in CollectionRoadmap.svelte so dependency lines between tasks render correctly across all viewport sizes and scroll positions.

2. Task preview opens on correct click — Fixed RoadmapItemPreview.svelte to open the task detail preview only when clicking the task bar itself, not when clicking whitespace or dependency arrows.

Changes

• frontend/src/lib/features/collections/CollectionRoadmap.svelte: Rewrote arrow coordinate calculation to use consistent reference points
• frontend/src/lib/features/collections/RoadmapItemPreview.svelte: Narrowed click handler to the task bar element only

Testing

• Verified dependency arrows render correctly at various zoom levels and scroll positions
• Confirmed task preview opens only on task bar click, not on arrows or empty space
• No existing tests affected (UI-only fixes)