feat: opt-in safe JSON parsing for large integer IDs (v1.7.0)

[JJ-Cro]

Summary

Proof of concept for sieblyio/gateio-api#101: Gate order IDs above Number.MAX_SAFE_INTEGER lose precision when responses are parsed with JSON.parse. This adds an opt-in, dependency-free text scanner and wires it into REST (axios) and WebSocket message parsing.

Changelog (1.7.0)

• src/lib/jsonParse.ts: quoteLossyIntegers(text) walks JSON text (respecting strings/escapes) and wraps only integer literals whose magnitude exceeds Number.MAX_SAFE_INTEGER in quotes. parseJSONSafeIds(text) = JSON.parse(quoteLossyIntegers(text)).
• REST (BaseRestClient): optional keepIdsAsString and customParseJSONFn on RestClientOptions (default off). When enabled, uses responseType: 'text' and a transformResponse that parses with the scanner or custom fn.
• WebSocket (WebsocketClient.resolveEmittableEvents): same options on WSClientConfigurableOptions for the single JSON.parse path.
• Tests: test/lib/jsonParse.test.ts covers root/nested/array ids, negatives, strings (including escapes), decimals/exponents, safe ints, and parity with JSON.parse when no lossy ints.
• Benchmark: scripts/benchmark-json-parse.ts (run after npm run build).

Benchmark (1000 bid + 1000 ask levels, 200 iterations)

Parser	Total	Per op
JSON.parse	130.07 ms	0.650 ms/op
parseJSONSafeIds	485.31 ms	2.427 ms/op

Ratio: ~3.73× slower than plain JSON.parse on this payload (expected: extra scan pass before parse).

npm run build && node --experimental-strip-types scripts/benchmark-json-parse.ts

Usage

const rest = new RestClient({ keepIdsAsString: true });
const ws = new WebsocketClient({ keepIdsAsString: true });
// or: customParseJSONFn: (text) => parseJSONSafeIds(text)

Response typings are unchanged; with the flag off, behaviour is identical to before.

CI / local checks

• npm run lint — pass
• npm run build — pass
• npm test — 11/11 new jsonParse tests pass; 23/30 total pass (7 existing test/REST/private.test.ts failures: missing API keys in this environment, unchanged by this PR)

Notes

• No new dependencies.
• CHANGELOG.md not edited (per fork workflow); release notes above.