Add "My points" from rewards contract

[joelpeace48-cell]

Call the deployed rewards contract balance(user) via Soroban RPC and display the result for the connected wallet. Handle not deployed / RPC errors.

[gracekenn]

@gracekenn has applied to work on this issue as part of the Stellar Wave Program's 3rd wave.

Please kindly assign me this task

ℹ️ Repo Maintainers: To accept this application, review their application or assign @gracekenn to this issue.