ankush10abc/matchinetaskmumbai ? reverse-engineered prompt

Build me a Flutter app called TradeDesk, a simple trading dashboard that works fully offline with a local mock market feed. It should show live prices for 10 NSE instruments that update every 900ms, and the whole app should feel like a real trading screen.

I want multiple watchlists that stay saved after the app restarts, with the ability to create them, rename them, add symbols, reorder items, and swipe to remove. Add a buy and sell ticket that shows the live LTP, checks the quantity, and makes sure the user can’t buy more than their balance or sell more than their holdings. Keep the wallet balance, holdings, watchlists, and order confirmations stored locally.

Also include a portfolio view that shows live P and L and lets me sort by P and L, symbol, or current value. Make the UI clean and easy to use on mobile, and if you need anything unclear, look up the latest Flutter docs online and keep it simple.