feat: migrate timestamps to int64 and security improvements

- Convert all time.Time fields to int64 Unix milliseconds (UTC)
- Add PostgreSQL migration to convert timestamp columns to bigint
- Reduce Binance sync window from 7 days to 24 hours
- Fix dashboard trader name visibility (add nofx-text-main color)
- Add position value column to history table
- Remove hardcoded API keys from test files

web/tailwind.config.js

@@ -21,6 +21,7 @@ export default {
         'nofx-accent': '#00F0FF', // Cyan Cyber
         'nofx-text': {
           DEFAULT: '#EAECEF',
+          main: '#EAECEF',
           muted: '#848E9C',
         },
         'nofx-success': '#0ECB81',