feat: add topology edge editor

[zshleon]

Task

Closes or implements: topology-edge-editor

Summary

Implemented an edge property editor in the Topology page, allowing users to specify the link type (Ethernet, WiFi, or Unknown) for each connection in their network.

Changes

• Edge Property Panel: Added a dedicated properties section in TopologyPage.tsx that activates when a connection line (edge) is clicked.
• Link Type Selection: Users can now toggle between:
  • Ethernet (Wired): Solid line styling.
  • WiFi (Wireless): Dashed line styling for clear visual distinction.
  • Unknown / Legacy: Default state with standard labels.
• Visual Distinction:
  • Ethernet connections use a solid, darker stroke.
  • WiFi connections use a dashed stroke (strokeDasharray: "5,5").
  • Selected edges are highlighted with a thicker stroke and darker color.
• Persistence: The chosen link_type is saved to the backend via the saveTopology endpoint and correctly restored on page reload.
• New Link Defaults: Newly created manual connections default to link_type: "unknown" but can be edited immediately.
• TypeScript Fixes: Added explicit typing for edge mapping to resolve build warnings.

Test Plan

• Backend checks run (python -m compileall app passed)
• Frontend build run (npm run build passed)
• Manual verification:
  • Click an edge -> Properties panel shows link type options.
  • Select "WiFi" -> Edge line becomes dashed instantly.
  • Select "Ethernet" -> Edge line becomes solid instantly.
  • Click Save -> Data persists and restores correctly after reload.
  • Click Pane -> Edge deselects, panel returns to default state.

Compatibility

• Does not overwrite manual layout positions
• Does not require database migration
• Does not change Docker/LXC permissions

Notes

The editor provides a clean, segmented-control-like UI for selecting link types, fitting the minimal homelab aesthetic of the project.