Fix dashboard and status rail rendering

[makerjackie]

Summary

• rebuild the dashboard surface with SwiftUI so the content no longer renders black
• replace the floating rail material with an opaque adaptive palette and truly transparent rounded corners
• keep quota state readable with labels, accessible icon controls, and light/dark appearance support
• bump the app to 0.7.1 (build 9)

Verification

• ./test.sh
• visually rendered and inspected the dashboard and floating rail in Aqua and Dark Aqua
• verified transparent rail corners in a window-level capture