Cline rules

1# Testing Rules
2 
3- Vitest with globals (describe, it, expect — no imports)
4- In-memory SQLite for all DB tests (`:memory:`)
5- Co-located: __tests__/*.test.ts or *.test.ts
6- Use Brain class directly for integration tests
7- Each test creates its own Brain instance
8- No SQLite mocking — use real in-memory DB
9- Test happy path + error cases
10- Run: pnpm test (all) or cd packages/core && pnpm test (single)
11