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>

vitest.config.ts

@@ -0,0 +1,23 @@
+import { defineConfig } from 'vitest/config'
+import react from '@vitejs/plugin-react'
+
+export default defineConfig({
+  plugins: [react()],
+  test: {
+    globals: true,
+    environment: 'jsdom',
+    setupFiles: './src/test/setup.ts',
+    css: true,
+    coverage: {
+      provider: 'v8',
+      reporter: ['text', 'json', 'html'],
+      exclude: [
+        'node_modules/',
+        'src/test/',
+        '**/*.config.ts',
+        '**/dist/',
+        '**/*.d.ts'
+      ]
+    }
+  },
+})