add a progress indicator during token transfers

I participated in the Common.fi testnet and found the overall experience very smooth.

Connecting the wallet and shielding tokens was easy and intuitive.

However, I noticed that the UI could be slightly more responsive when switching between the Public and Shielded menus.

Also, it would be helpful to add a progress indicator during token transfers.

Overall, it's a great platform with a lot of potential. Looking forward to the mainnet launch!