Add Playwright assistant regression coverage

frontend/playwright.config.ts

@@ -0,0 +1,52 @@
+import fs from "node:fs";
+import path from "node:path";
+import { fileURLToPath } from "node:url";
+import { defineConfig } from "@playwright/test";
+
+// Demo specs log in with the real dev credentials; pull them from the repo
+// .env so they never live in the test source.
+const repoEnv = path.resolve(path.dirname(fileURLToPath(import.meta.url)), "../.env");
+if (fs.existsSync(repoEnv)) {
+  for (const line of fs.readFileSync(repoEnv, "utf8").split("\n")) {
+    const m = line.match(/^([A-Z_]+)=["']?(.*?)["']?$/);
+    if (m && !(m[1] in process.env)) process.env[m[1]] = m[2];
+  }
+}
+
+export default defineConfig({
+  testDir: "./e2e",
+  outputDir: "./test-results",
+  fullyParallel: false,
+  // Demo runs synthesize narration and run several ffmpeg passes in save();
+  // that can exceed the 30s default, especially with many steps.
+  timeout: process.env.PW_DEMO ? 120_000 : 30_000,
+  reporter: [
+    ["list"],
+    ["html", { outputFolder: "playwright-report", open: "never" }],
+  ],
+  use: {
+    baseURL: "http://localhost:3000",
+    // Demo runs (pnpm demo) pace every action so the recorded video is
+    // watchable by a human; functional e2e runs stay at full speed.
+    launchOptions: {
+      slowMo: process.env.PW_DEMO ? 500 : 0,
+    },
+    locale: "es-CR",
+    timezoneId: "America/Costa_Rica",
+    viewport: { width: 1920, height: 1080 },
+    // Retina-density rendering so doc screenshots stay crisp when zoomed.
+    deviceScaleFactor: 2,
+    // Full recordings are only useful for the paced demo. Keeping them off
+    // for regular e2e avoids making test success depend on artifact uploads.
+    video: process.env.PW_DEMO ? { mode: "on", size: { width: 1920, height: 1080 } } : "off",
+    screenshot: "only-on-failure",
+    trace: process.env.PW_DEMO ? "on" : "on-first-retry",
+  },
+  webServer: {
+    command: "pnpm dev",
+    url: "http://localhost:3000",
+    reuseExistingServer: true,
+    stdout: "ignore",
+    timeout: 60_000,
+  },
+});