Redesign approval UI

[maxmalkin]

Summary

Overhauls the approval UI with an industrial/utilitarian dark theme:

• Dark theme: Near-black surface, dark gray panels, sharp edges (no border-radius)
• Typography: JetBrains Mono for data/IDs, DM Sans for body text
• Color system: Amber accents for primary actions, color-coded status indicators (green/amber/red)
• Loading states: Skeleton shimmer animations replace spinners
• Animations: Staggered fade-in for content sections, slide-up for modals
• Layout: Dense data display with monospace section labels, mission control aesthetic
• Tailwind CSS: Added via CDN for utility-first styling