apply eslint and typescript checks on tests too

[severo]

No description provided.

[Copilot]

Pull request overview

This PR restructures TypeScript config usage so that both ESLint’s type-aware rules and tsc typechecking cover the test/ directory, while keeping the declaration build limited to src/.

Changes:

• Split TS configs into a build-focused tsconfig.build.json and a repo-wide tsconfig.json (noEmit) that includes tests.
• Remove tsconfig.eslint.json and point ESLint’s parserOptions.project at tsconfig.json.
• Update scripts and adjust a couple tests for stricter indexed access typing.

Reviewed changes

Copilot reviewed 6 out of 7 changed files in this pull request and generated 4 comments.

Show a summary per file

File	Description
tsconfig.json	Makes tsc/ESLint type-aware checks include test/ (and broader globs) with noEmit.
tsconfig.eslint.json	Removed in favor of using tsconfig.json directly.
tsconfig.build.json	New build-only TS config used for declaration output (dist/types).
test/providers/DataProvider.test.tsx	Adds guard to satisfy strict indexed access typing.
test/helpers/dataframe/array.test.ts	Adds guard to satisfy strict indexed access typing.
package.json	Uses tsconfig.build.json for type build; typecheck now runs plain tsc.
eslint.config.js	Points type-aware TS ESLint config to tsconfig.json.

---

💡 Add Copilot custom instructions for smarter, more guided reviews. Learn how to get started.