sdk: restore JSON-RPC batch correctness

[0xjc65eth]

Fixes #161

/claim #161
Payment: BTC | bc1qjf2t6dc75c6t2948essyrqec0a08l8zl28fcfh | Bitcoin

Summary:

• Match JSON-RPC batch responses by id instead of response array position.
• Preserve original request order in the returned array.
• Return per-item error objects for partial JSON-RPC failures.
• Return per-item timeout errors for missing response ids.
• Abort a hung batch request with a configurable timeout and return timeout errors for every request.
• Add tests for shuffled response order, partial failure, missing response timeout, and whole-batch timeout.
• Add top-of-file contributor metadata and CONTRIBUTORS.json runtime metadata.

Verification:

• npx mocha test/SDKRpcBatchOrdering.test.js -> 4 passing
• npx tsc --noEmit --ignoreConfig --target ES2020 --module commonjs --types node sdk/src/providers/rpc.ts -> clean
• node --check test/SDKRpcBatchOrdering.test.js -> clean
• CONTRIBUTORS.json parses as valid JSON
• git diff --check -> clean

Competing PR review:

• Reviewed the competing RPC batch implementation and flagged a missing whole-batch timeout path before submitting this PR.