Handle backend-unavailable and empty states gracefully across data pages

[priscaenoch]

Problem

Many pages assume the indexer responds successfully. When the backend is down or returns no data, users can see blank screens or unhandled errors rather than actionable messaging. This compounds the fact that the production API base is currently misconfigured.

What needs to be done

• Audit the data pages (Home, ContractPage, EventPage, SearchPage, WalletPage, GraphPage, dashboards) for missing empty/error handling.
• Add consistent empty states ("no results") and error states ("couldn't reach the backend, retry") using the shared query/error handling.
• Ensure errors from the API client are surfaced, not swallowed.

Files

• the data pages listed above
• shared error/empty-state components under src/components

Acceptance deliverables

• Every audited page renders a defined empty state and a defined error state.
• No page renders a permanently blank view on backend failure.

Tests to pass

• Tests for at least three pages assert the empty state and the error state render as expected.

[pharuq411]

i will like to work on this issue based on my experience

[grantfox-oss]

🦊 GrantFox — @pharuq411 has been assigned to this issue as part of the Official Campaign | FWC26 campaign!

Next steps:

1. Open a Pull Request referencing this issue (e.g., Closes #12)
2. Your PR will be reviewed by the octraban maintainers

Good luck! Track your progress on GrantFox.

[grantfox-oss]

🎉 This issue has been marked as completed on GrantFox as part of the Official Campaign | FWC26 campaign!

@pharuq411's PR #32 was approved and merged by @priscaenoch.

🏆 @pharuq411: You earned 35 FoxPoints for this contribution! Your current tier: Explorer (452 total points). Track your full progress on GrantFox.

👏 Great work, @pharuq411! Keep contributing to octraban.