[Eco Bounty] Missing Transaction Signature Validation in “Submit transaction Signature and Slot” Popup

Wallet Address:
0x0f06443fbfc0Eb7D1f1c98DC74005546e2f70AAb

Bug Description:
On the https://bridge.iotex.io website, users can enter an invalid transaction signature (e.g., "Thai 5r") in the “Submit transaction Signature and Slot” popup, and the form still allows submission without any validation or error feedback. This can lead to confusion or backend issues.

Device & Testing Environment:

• Device: Dell Laptop

• OS: Ubuntu

• Browser: Chrome

Steps to Reproduce:

1. Go to: https://bridge.iotex.io

2. Click on the Transactions tab

3. Choose either IoTeX or ETH

4. Click: “Can’t find your transaction? Submit your Solana Tx here”

5. In the popup, enter an invalid string like “Thai 5r” into the Transaction signature field

6. Click Confirm

7. Notice that no validation or error message appears

Actual Result:

• The form accepts malformed input without any error or blocking the submission

Expected Result:

• Input should be validated against the Solana signature format (base58, ~88 characters)

• Inline error should be displayed for invalid input

• Form should prevent submission when data is invalid