react: split out @sentriscloud/sdk-ts-react with hooks (useChainTip, useBalance, useSubscribe)

[satyakwok]

Wrap the SDK's chain reads + subscriptions in idiomatic React hooks. Ship as a sibling package (@sentriscloud/sdk-ts-react) or sub-export so dApp builders don't have to write the useEffect/useState dance themselves.

Scope

• useChainTip() — current height, auto-updating via newHeads subscription
• useBlock(blockNumber | hash) — fetch + cache a block
• useBalance(address) — native or ERC-20 balance, re-fetches on new block
• useTransaction(hash) — tx + receipt
• useSendTransaction() — write hook with wallet integration
• Internal cache layer (React Query underneath, optional)

Why

Every dApp on Sentrix reimplements these. A canonical package = consistent UX + faster build time.

Out of scope

• Wallet connector logic (WalletConnect / RainbowKit) — those have their own libraries; this package consumes their connection result
• Storybook / docs site — separate effort