User Experience (UX) Enhancements

[samarkun23]

• Loading States: Add a loadingQuotes state in SwapWidget.tsx. Currently, when a user types an amount, the UI doesn't provide feedback while it's fetching quotes from multiple DEXes.
• Balance Validation: Fetch the user's balanceOf for the input token. If amountIn > balance, disable the "Trade" button and show an "Insufficient Balance" warning.
• Price Impact: Calculate and display the Price Impact. If a trade is too large for the available liquidity, warn the user so they don't lose money to slippage.