#3929-Gantt-Chart-Improvements fix WP showing multiple times if it has multiple dependencies

[RemainingDelta]

Changes

Previously, a Work Package (WP) with multiple dependencies would render once per dependency, causing the same WP bar to appear multiple times on the Gantt chart. This PR fixes that by ensuring each WP renders exactly once, with red arrows drawn from all its dependencies to that single instance.

Notes

• Uses react-archer for arrow rendering
• WBS numbers determine which parent a blocked WP renders under

Test Cases

• A WP with a single dependency shows one arrow
• A WP with multiple dependencies renders once with multiple arrows pointing to it
• A WP with no dependencies renders normally with no arrows

Screenshots

Closes #3929