Add agent hierarchy/workflow view to Network page

[D0NMEGA]

Problem

The Network page shows all agents in a flat graph. Users need to see their agents in a boss/subordinate hierarchy.

Acceptance Criteria

• Toggle between network view and workflow view
• Drag-and-drop positioning in workflow mode
• Positions saved to backend or localStorage
• Only show user's agents + direct connections

Suggested Approach

Use d3-force with custom forces to create hierarchical layout. Save positions via localStorage initially.