[UX] Improve Wallet Selector Connection Feedback

[emdevelopa]

Description

The WalletSelector lacks clear feedback when a connection attempt fails or is pending.

Requirements and context

• Add a loading spinner or "Connecting..." state to the selected wallet button.
• Implement user-friendly error messages (e.g., "User rejected request", "Extension not found").
• Ensure the modal remains responsive during async operations.

Suggested execution

1. Update state management in WalletSelector.tsx to include a loading and error state.
2. Catch errors from wallet provider promises and map them to friendly messages.
3. Add visual feedback (disabled buttons, spinners).

Test and commit

• Mock a failed connection and verify the error message appears.
• Verify the connecting state is shown during the handshake.

Guidelines

• Error messages should be helpful, not technical.
• PR description must include: Closes #[issue_id]

Complexity: Medium (150 points)

[shogun444]

@shogun444 has applied to work on this issue as part of the Stellar Wave Program's 3rd wave.

I'd love to work on this.

ℹ️ Repo Maintainers: To accept this application, review their application or assign @shogun444 to this issue.