AB#108653 Document LTI helpers via .d.ts and update README helper ove…

[sebastianchristopher]

…rview

• moves the documentation into a dedicated testUtils.d.ts so IntelliJ/TS show rich hover docs, while keeping testUtils.js as implementation-only
• simplifies the package exports around testUtils/config without changing runtime behaviour

[Copilot]

Pull request overview

This PR improves the documentation of LTI test helper functions by creating a dedicated TypeScript declaration file (.d.ts) that provides rich IDE hover documentation, while keeping the JavaScript implementation file clean and free of JSDoc comments.

Key changes:

• Moved JSDoc documentation from testUtils.js to a dedicated testUtils.d.ts file for better IDE integration
• Added TypeScript and @types/node as dev dependencies to support declaration file generation
• Enhanced README with a comprehensive "Helper overview" section documenting the API and usage patterns

Reviewed changes

Copilot reviewed 4 out of 6 changed files in this pull request and generated 1 comment.

Show a summary per file

File	Description
tsconfig.types.json	New TypeScript configuration for generating type declarations from JavaScript files
src/testUtils.js	Removed all JSDoc comments, keeping only implementation code
src/testUtils.d.ts	New TypeScript declaration file with comprehensive documentation including usage examples and detailed descriptions
package.json	Updated build script to generate and copy type declarations; added TypeScript tooling dependencies; included src/testUtils.js in published files; removed obsolete @rollup/plugin-node-resolve dependency
package-lock.json	Reflects dependency changes - removed Rollup plugin and its transitive dependencies, added TypeScript and Node type definitions
README.md	Added "Helper overview" section with environment variable documentation, core helper descriptions, and end-to-end usage example

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[Copilot]

[nitpick] Including src/testUtils.js in the published package appears unnecessary since the built version in dist/testUtils.js is what's actually used (via the main and module fields). Unless this is needed for source maps or debugging purposes, consider removing it to reduce package size. The TypeScript declaration file dist/testUtils.d.ts already provides type information for consumers.

Suggested change

"src/testUtils.js",