Feature Request: Add `useExplorerLink()` + consistent explorer link rendering across components

### Describe the solution you'd like

### Common developer pain points:
- Manually constructing explorer URLs for `txHash`, `address`, `blockNumber`, `token`, etc.
- Needing different explorers depending on chain (Base vs Ethereum) and network (mainnet vs testnet).
- Inconsistent link text, target behavior, and formatting across different OnchainKit components.
- Duplicated logic across apps for something that should be standardized.

### Expected Behavior
- Developers can reliably generate explorer links from chainId + identifier.
- Links are correct for Base Mainnet and Base Sepolia (and any supported chain).
- UI components that show tx hashes or addresses can optionally render a consistent “View on Explorer” link.

### Describe alternatives you've considered.

### Proposed Solution

- Add a small utility + hook:
- getExplorerUrl({ chainId, type, value })
- useExplorerLink({ chainId, txHash?, address?, blockNumber?, tokenAddress? })
- Maintain a centralized mapping of supported chainId -> explorerBaseUrl (BaseScan for Base networks).
- Provide a tiny UI helper component (optional):
- Update relevant components/examples that currently print raw hashes to optionally include a consistent explorer link.