Separates graph panning from selection-gated drag by updating `useNodeDrag` and `useGraphInteraction` hooks to handle the two interaction modes independently, with `GraphTaskNode` now gating drag on selection state. Tests were added across the graph interaction, node drag, persistence, and integrati
Fusion-Task-Id: FN-3941
Documentation-only finish for FN-3087, adding changeset and README updates for the dependency graph plugin and plugin authoring guide.
Fusion-Task-Id: FN-3087
Adds draggable interaction to dependency graph nodes (FN-3089), introducing a `useNodeDrag` hook to manage drag state and positioning, with corresponding tests and a new drag stylesheet; the `GraphTaskNode` and `DependencyGraph` components are updated to wire up the drag behavior.
Fusion-Task-Id: FN-3089
