fix: ensure all timestamps use UTC timezone

- Add NowFunc to GORM config for UTC auto-generated timestamps
- Add .UTC() to all time.UnixMilli() calls in trader files
- Add .UTC() to all time.Now() calls in store and api files
- Fix TypeScript unused imports in frontend

web/src/components/DeepVoidBackground.tsx

@@ -1,5 +1,4 @@
 import React from 'react'
-import { motion } from 'framer-motion'
 
 interface DeepVoidBackgroundProps extends React.HTMLAttributes<HTMLDivElement> {
     children?: React.ReactNode