Create AGENTS.md file for SCORE project

### What

Create AGENTS.md file for SCORE repository

**Why AGENTS.md?**

README.md files are for humans: quick starts, project descriptions, and contribution guidelines.

AGENTS.md complements this by containing the extra, sometimes detailed context coding agents need: build steps, tests, and conventions that might clutter a README or aren’t relevant to human contributors.

In the current world of AI, AGENTS.md give agents a clear, predictable place for instructions.

### Acceptance Criteria (DoD)

Below mentioned are sample AGENTS.md content based on different use cases.

## Dev environment tips
- Use `pnpm dlx turbo run where ` to jump to a package instead of scanning with `ls`.
- Run `pnpm install --filter ` to add the package to your workspace so Vite, ESLint, and TypeScript can see it.
- Check the name field inside each package's package.json to confirm the right name—skip the top-level one.

## Testing instructions
- Find the CI plan in the .github/workflows folder.
- Run `pnpm turbo run test --filter ` to run every check defined for that package.
- From the package root you can just call `pnpm test`. The commit should pass all tests before you merge.
- To focus on one step, add the Vitest pattern: `pnpm vitest run -t ""`.
- Fix any test or type errors until the whole suite is green.

## PR instructions
- Title format: []
- Always run `pnpm lint` and `pnpm test` before committing.

### How

_No response_