fix: prevent transitions from overlapping in workflow graph (#22)

[kamleshyadav9929]

Description

Fixes #22 - Transitions overlapping in the workflow graph.

Problem

When multiple transitions originate from the same state, they visually overlap making the graph hard to read.

Solution

Modified CustomEdge.tsx to:

1. Detect edges sharing the same source node (sibling edges)
2. Calculate index-based curve offsets to spread edges apart
3. Apply different curvature to each edge based on its position

Technical Changes

• Added edgeIndex and totalSiblingEdges detection in the store selector
• Implemented curvatureOffset calculation based on edge index
• Switched from getSmoothStepPath to getBezierPath for smoother curves
• Applied index-based offset when multiple edges share the same source

Files Changed

• src/components/Graph/Edges/CustomEdge.tsx