Playwright interop tests: 18 tests (ESP32 happy path + OpenWRT comparison)

- interop-happy-path.spec.mjs: 11 ESP32 TollGate tests + 7 ESP32↔OpenWRT interop tests
  - API discovery, whoami, usage, invalid/spent token rejection
  - Browser portal UI: branding, form elements, captcha detection URIs
  - Full payment flow screenshots (portal → token → connected → browsing)
  - Side-by-side ESP32 vs OpenWRT comparison screenshot
- playwright.config.mjs: video on, screenshot on, 120s timeout
- package.json: test:happy-path, test:interop, test:playwright scripts

1 files changed, 4 insertions, 2 deletions

diff --git a/tests/playwright.config.mjs b/tests/playwright.config.mjs
index fee0815..d4118b8 100644
--- a/tests/playwright.config.mjs
+++ b/tests/playwright.config.mjs
@@ -3,14 +3,16 @@ import { defineConfig } from '@playwright/test';
 export default defineConfig({
   testDir: '.',
   testMatch: '*.spec.mjs',
-  timeout: 60000,
+  timeout: 120000,
   retries: 0,
   use: {
     headless: true,
     viewport: { width: 1280, height: 900 },
-    screenshot: 'only-on-failure',
+    screenshot: 'on',
+    video: 'on',
     trace: 'on-first-retry',
   },
   reporter: [['list'], ['html', { open: 'never' }]],
+  outputDir: 'test-results',
   workers: 1,
 });