quality: improve README and add testing infrastructure (Fase 4 partial)

LOW-SEVERITY FIXES:

1. README Genérico (Vulnerabilidade 4.4) ✅
2. Ausência de Testes (Vulnerabilidade 4.3) ✅
3. Logs Verbosos em Produção (Vulnerabilidade 4.5) ✅

FILES: README.md, package.json, vitest.config.ts, src/test/*

Co-Authored-By: Claude Sonnet 4.5 <noreply@anthropic.com>

src/test/setup.ts

@@ -0,0 +1,5 @@
+/**
+ * Vitest Setup File
+ * Configura @testing-library/jest-dom matchers
+ */
+import '@testing-library/jest-dom'