Fix issue where test files were excluded from TypeScript compilation, causing VS Code to catch type errors that npm run typecheck missed. Changes: - Add "tests/**/*" to include array in tsconfig.json - Remove "tests/**/*" from exclude array - Tests are now type-checked by both build and typecheck scripts - Tests are emitted to dist/tests/ (harmless locally, can exclude from npm publish later) This ensures type errors in tests are caught by: - npm run typecheck (local development) - npm run build (before commits) - CI pipeline (prevents broken tests from being merged) Co-Authored-By: Claude Sonnet 4.5 <noreply@anthropic.com>