feat(contracts): implement guild owner lookup

[h1065153539-create]

Summary

/claim #12

Implements ContractClient.getGuildOwner so SDK users can fetch guild ownership from the configured contract instead of receiving NOT_IMPLEMENTED.

Changes

• Adds a typed GuildOwnerParams contract method input.
• Validates guildId, rpcUrl, and contract address before making network calls.
• Encodes supported guild IDs as bytes32 and sends an eth_call to getGuildOwner(bytes32).
• Decodes and validates the returned owner address.
• Surfaces clear SDK errors for missing config, RPC failures, and malformed RPC responses.
• Documents usage in README, SDK guide, and API reference.

Testing

• npm.cmd run typecheck - passed
• npm.cmd run test:run - passed, 101 tests
• npm.cmd run build - passed
• npm.cmd run test:smoke - passed ESM/CJS/type smoke checks
• npm.cmd run lint - exited 0 with existing repository warnings only
• git diff --check - passed

Security / compatibility notes

• The implementation uses standard JSON-RPC eth_call only; it does not sign transactions or mutate chain state.
• No secrets, private keys, API keys, or wallet credentials are logged or added.
• Existing contract stubs for token balance and role requirements keep their current behavior.

[h1065153539-create]

Refreshed this PR at 4647fa2 on top of current main (�fa3297) after the chain-aware contract config landed.

What changed in the refresh:

• Kept getGuildOwner, but now resolves
  pcUrl / contractAddress through getChainConfig(params.chainId).
• Added optional per-call chainId support while preserving per-call contractAddress overrides.
• Kept the newly merged chain config tests passing alongside guild-owner lookup coverage.

Validation run locally:

pm run test:run -- tests/contracts.test.ts tests/client.test.ts -> 26 tests passed

pm run typecheck -> passed

pm run build -> passed

PR status after refresh: mergeable clean.

[Lakes41]

Splendid implementation