fix: Address code review feedback

- Added explanation for logger mocking in tests/setup.ts
- Removed test files from coverage collection in jest.config.js
- Updated tests/README.md to clarify coverage approach and remove outdated threshold reference

Co-authored-by: mindesbunister <32161838+mindesbunister@users.noreply.github.com>

jest.config.js

@@ -19,7 +19,6 @@ const config = {
   setupFilesAfterEnv: ['<rootDir>/tests/setup.ts'],
   collectCoverageFrom: [
     'lib/trading/position-manager.ts',
-    'tests/**/*.ts',
   ],
   coverageReporters: ['text', 'text-summary', 'html'],
   verbose: true,