Document the frontend/backend indexer contract and add a connection health check

[priscaenoch]

Problem

The frontend depends on the Octraban indexer (default http://localhost:3001) for all /api/* data, but there is no in-repo documentation of that dependency and no user-facing signal when the backend is unreachable. The relationship is only implicit in scattered fetch calls.

What needs to be done

• Document, in the README, the endpoints the frontend consumes and the expected backend (octraban_backend indexer on :3001), including the port topology (API :3000, indexer :3001).
• Add a lightweight startup/connection check against the backend health endpoint and show a clear, non-blocking banner when the indexer is unreachable, with the configured URL.
• Link the backend repository from the README's setup section.

Files

• README.md
• new src/components/BackendStatusBanner.tsx (or extend an existing banner component)
• src/App.tsx

Acceptance deliverables

• README documents the frontend/backend contract and ports.
• When the backend is down, the app shows a clear banner instead of silent failures.

Tests to pass

• Test: banner appears when the health check fails and is hidden when it succeeds (API client mocked).

[GBOYEE]

Hey! The frontend's dependency on the Octraban indexer on :3001 is undocumented and silent when down. I'll add the endpoint/port topology (API :3000, indexer :3001) and a backend repo link to README.md, plus a lightweight health-check banner component (src/components/BackendStatusBanner.tsx) wired into App.tsx that shows a non-blocking notice with the configured URL when the indexer is unreachable. Mind if I take this on? I'll have it ready by tomorrow.

[pharuq411]

i will like to work on this issue based on 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 #11)
2. Your PR will be reviewed by the octraban maintainers

Good luck! Track your progress on GrantFox.