[codex] redesign admin dashboard

[xiaokangzaina]

Summary

• Redesign the console dashboard into a denser, light-mode-friendly admin workspace with a compact header, quick range controls, metric cards, analytics panel, and side rail panels.
• Keep the existing dashboard data hooks, API calls, chart data flow, and route structure intact while moving the layout/styling into scoped dashboard classes.
• Add a small Bun structure test that locks the new dashboard landmarks and scoped CSS marker.

Why

The current dashboard layout is functional but less aligned with a compact API gateway admin workflow. This update makes the first screen easier to scan for balance, usage, resource consumption, performance, model analytics, API info, uptime, announcements, and FAQ content.

Validation

• bun test ./src/components/dashboard/__tests__/dashboard-layout.test.js
• bun run build
• Browser smoke check on local /console: quick range switch, search modal open/close, chart tab switching, desktop and 390px mobile viewport without horizontal overflow.

Notes

bun run build still reports existing project warnings for outdated Browserslist data, lottie-web eval usage, and large chunks. No dashboard-specific build warning remains.