Migrate remaining raw fetch calls to React Query for consistent loading, error, and caching

[priscaenoch]

Problem

The app already wires QueryClientProvider in src/main.tsx and uses useQuery in some components (e.g. AddressConnectionGraph.tsx, CircuitBreakerStatus.tsx, ContractDependencyGraph3D.tsx), but several pages fetch with raw fetch and manual useState/useEffect, giving inconsistent loading states, no caching, and duplicated error handling. Examples: src/pages/RpcMetricsDashboard.tsx, src/pages/RateLimitDashboard.tsx, src/pages/BatchMultiCall.tsx, src/pages/SetupPage.tsx.

What needs to be done

• Convert the manual-fetch pages to useQuery/useMutation (reads vs. actions), using the shared API client.
• Standardize loading and error UI via the query state (isLoading, error).
• Configure sensible defaults (retry, staleTime) on the QueryClient where appropriate.

Files

• src/main.tsx (query defaults)
• src/pages/RpcMetricsDashboard.tsx, src/pages/RateLimitDashboard.tsx, src/pages/BatchMultiCall.tsx, src/pages/SetupPage.tsx

Acceptance deliverables

• The listed pages use React Query for all reads/writes.
• Loading and error states are derived from query state, not ad hoc flags.

Tests to pass

• Tests for at least one converted page assert loading, success, and error rendering (with the API client mocked).
• Existing tests continue to pass.

[grantfox-oss]

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

@jrcity's PR #35 was approved and merged by @priscaenoch.

🏆 @jrcity: You earned 35 FoxPoints for this contribution! Your current tier: Explorer (118 total points). Track your full progress on GrantFox.

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