## What

Brief description of the change.

## Why

What problem this solves or what feature it adds.

## How

Key implementation details. Mention any non-obvious decisions.

## Testing

- [ ] `npx tsc --noEmit` passes
- [ ] `npm run build` succeeds
- [ ] `npx vitest run` — all tests pass
- [ ] New tests added for new functionality
- [ ] Manually tested the change

## Checklist

- [ ] No new TypeScript errors
- [ ] No new ESLint warnings
- [ ] Version bumped if this is a release
- [ ] README updated if user-facing behavior changed
- [ ] No secrets or API keys in the diff
