test(e2e): migra gli end-to-end a CommonJS e stabilizza l'esecuzione Playwright

- aggiunge configurazione playwright.config.cjs per compatibilita runtime
- aggiorna playwright.config.ts con progetto Mobile Chrome
- migra i test E2E da .js a .spec.cjs
- rimuove i vecchi file E2E non piu usati
- allinea i test visual con snapshot baseline aggiornate

playwright.config.cjs

@@ -0,0 +1,38 @@
+const { defineConfig, devices } = require('@playwright/test');
+
+/**
+ * See https://playwright.dev/docs/test-configuration.
+ */
+module.exports = defineConfig({
+  testDir: './tests/e2e',
+  fullyParallel: false,
+  forbidOnly: !!process.env.CI,
+  retries: process.env.CI ? 2 : 0,
+  workers: 1,
+  reporter: 'html',
+  use: {
+    trace: 'on-first-retry',
+  },
+
+  projects: [
+    {
+      name: 'chromium',
+      use: { ...devices['Desktop Chrome'] },
+    },
+    {
+      name: 'firefox',
+      use: { ...devices['Desktop Firefox'] },
+    },
+    {
+      name: 'Mobile Chrome',
+      use: { ...devices['Pixel 5'] },
+    },
+  ],
+
+  webServer: {
+    command: 'npm run serve',
+    url: 'http://localhost:3000',
+    reuseExistingServer: !process.env.CI,
+    timeout: 120 * 1000,
+  },
+});