[Eco Bounty] Wallet selection UI: Inconsistent state when switching wallets too quickly

Wallet Address:
0x0f06443fbfc0Eb7D1f1c98DC74005546e2f70AAb
Bug Description:
On the Buy screen, when a user clicks Connect Wallet and selects Metamask, the app starts processing the connection. However, if the user quickly clicks another wallet (Binance or WalletConnect) before Metamask finishes loading, the left-side list updates highlight, but the main area (QR/handle) does not update accordingly creating confusion.

Device & Testing Environment:
Device: Dell Laptop
OS: Ubuntu
Browser: Chrome

Steps to Reproduce:

1. Visit: https://hub.iotex.io

2. Click Connect Wallet

3. Choose Metamask

4. While it's still loading, click another wallet like WalletConnect

5. Observe: the sidebar changes, but the QR or main content does not update
   

Actual Result:
Sidebar changes to reflect the new wallet, but the main area still waits for the previous one → desynchronization

Suggested Improvement:
– Show a loading indicator while wallet connection is in progress
– Prevent multiple wallet selections during the loading state

→ This improves clarity and prevents spam-clicking or user confusion.