feat: improve strategy studio and fix trader deletion bug

- Add strategy export/import functionality to Strategy Studio
- Fix trader deletion not removing from memory (competition page ghost data)
- Simplify TraderConfigViewModal: remove unused fields, show strategy name
- Improve quant data formatting: OI/Netflow multi-timeframe display
- Add configurable OI/Netflow toggles in indicator settings
- Clean up unused frontend components and dead code

web/src/lib/utils.ts

@@ -1,6 +0,0 @@
-import { clsx, type ClassValue } from 'clsx'
-import { twMerge } from 'tailwind-merge'
-
-export function cn(...inputs: ClassValue[]) {
-  return twMerge(clsx(inputs))
-}