Add mobile wallet balance refresh control

[Brainoncrack]

Description

Difficulty: Intermediate

Type: Feature

Summary

Add a manual refresh control for wallet balance.

Current Behaviour

Users may not know whether displayed balance is current.

Expected Behaviour

The wallet screen should provide refresh feedback and last-updated state where possible.

Suggested Implementation

Add balance refresh action with loading, success, and failure states.

Files or Areas Likely Affected

app/
src/features/wallet/
src/components/

Acceptance Criteria

• Balance refresh action is added.
• Loading state is shown.
• Failure state is handled.
• Last-updated state is considered.
• No secrets are exposed.

Additional Notes

This supports tester confidence.