ci: add type tests for TypeScript 5.x to CI workflow

[fasttime]

Prerequisites checklist

• I have read the contributing guidelines.

AI acknowledgment

• I did not use AI to generate this PR.
• (If the above is not checked) I have reviewed the AI-generated content before submitting.

What is the purpose of this pull request?

add tests in CI

What changes did you make? (Give an overview)

Add type tests for TypeScript v5.3 and v.5.x besides existing tests targeting TypeScript v6.0.

Related Issues

refs #224

Is there anything you'd like reviewers to focus on?

[fasttime]

GitHub marks the comments in this file in red because it doesn't recognize tsconfig.dist.json as a TypeScript config file, so it falls back to plain JSON instead of JSONC. The syntax highlighting disappears if the file is renamed to dist.tsconfig.json, although that would not align with our conventions.

[Copilot]

Pull request overview

Adds additional CI coverage to ensure the published dist/ type definitions remain compatible with TypeScript 5.x (in addition to the existing TypeScript 6.x type tests).

Changes:

• Add a dedicated TS config for checking only dist/ with older TypeScript versions.
• Extend CI workflow to run tsc against dist/ using TypeScript 5.3 and latest 5.x via npx.
• Update ESLint flat config so tsconfig*.json files are linted as JSONC (to allow comments/trailing commas).

Reviewed changes

Copilot reviewed 3 out of 3 changed files in this pull request and generated 2 comments.

File	Description
tests/types/tsconfig.dist.json	New TS config intended for running tsc checks on dist/ under TS 5.x.
eslint.config.js	Lints tsconfig*.json as JSONC and enables trailing commas support.
.github/workflows/ci.yml	Adds CI steps to run TS 5.3 and 5.x tsc checks against dist/.

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[lumirlumir]

LGTM, thanks!