examples: expand beyond ERC-20 (NFT, multicall, signing, viem)

[satyakwok]

Starter currently focuses on ERC-20 deploy + WSRX wrapping per README. Add more example patterns so new dApp builders see the full surface available on Sentrix.

Scope

• ERC-721 mint example (uses canonical-contracts as base?)
• ERC-1155 mint example
• Multicall3 batched-read example
• viem typed-data signing example (EIP-712)
• ENS-style name resolution via Sentrix Names once shipped (cross-ref feat: Sentrix Names (.srx ENS-style naming service) sentrix-labs/sentrix#617)

Acceptance

• Each example in its own examples/<name>/ subdir
• README "Examples" section linking
• Each runs with pnpm run <example>