feat: multi-rack cable visualization

[ggfevans]

Parent Epic

Part of #71 (Network Interface Visualization and Connectivity)

Summary

Visualize cables that span multiple racks (when multi-rack support is implemented).

Prerequisites

• Multi-rack layout support (not yet implemented)
• This issue is for future planning

Challenges

1. Cable routing between distant racks
2. Visual scale (zoomed out = cables not visible)
3. Cross-rack cable length representation
4. Performance with many inter-rack cables

Visualization Options

1. Direct lines - Straight/curved lines between racks
2. Abstract markers - Show "exits to Rack-2" indicator
3. Separate view - "Topology" view without rack visualization
4. Expandable paths - Click to see full path

Acceptance Criteria

• Cables can reference devices in different racks
• Visual representation of inter-rack cables
• Cable trace works across racks
• Performance acceptable with many cables

Dependencies

• Multi-rack support (future epic)
• spike: cable path rendering algorithm #262 (Cable path rendering)

References

• NetBox cross-rack cables
• Device42 multi-rack visualization