[next-wave] Live testnet status widget on docs site

[Gbangbolaoluwagbemiga]

Context

LIVE_TESTNET.md documents three deployed contracts on Soroban Testnet:

• Runtime Guard Wrapper: CBLDEREKXK6AIZ7ZSKC6VYCK4MKF4FZ4ANJEU67QZAQUG57I4KGZMTXB
• Vulnerable Contract: CABBT5FKG7AE7IEEA4KR2J5AVYRSZAWKTXZ2KFX3UNJQAMMLMCXNLMIB
• Reentrancy Guard: CDDVM5A5IVDAG5FZ2OU2CLWAHC7A2T7LHQHZSDVKZPE6SDMDO2JCR3UY

Now we need a live status widget on the docs site that reads these contracts via Soroban RPC and shows their state in real time.

Tasks

• Add a <TestnetStatus> React component to the frontend
• Use @stellar/stellar-sdk to call health_check() and get_stats() on the Runtime Guard Wrapper
• Display: total_calls, successful_calls, failed_calls, last_call_ts (formatted as relative time)
• Poll every 30 seconds with a manual refresh button
• Show a red error state if the RPC is unreachable
• Add to the homepage hero (above the fold) and to a new /testnet route
• Cypress smoke test for the route loading

Acceptance Criteria

• Numbers visible on the deployed Vercel site match stellar contract invoke ... -- get_stats
• Polling does not block page interactivity (uses useEffect + cleanup)
• Component is keyboard navigable and announces updates to screen readers