fix: only use local system Chromium in Playwright config outside CI

The blocking carpenter smoke test (introduced in this branch) exposed
a pre-existing gap: playwright.config.js hardcoded
executablePath: '/snap/bin/chromium' plus channel: 'chromium' for the
maintainer's local CachyOS machine. CI has no /snap/bin/chromium (it
installs its own Chromium via `playwright install --with-deps
chromium`), so every CI run was silently failing to launch the browser
- previously masked because the whole E2E step had
continue-on-error: true.

Gate both overrides behind `!process.env.CI` so local runs keep using
system Chromium and CI falls back to its own installed browser.

Co-Authored-By: Claude Sonnet 5 <noreply@anthropic.com>

tests/playwright.config.js

@@ -29,8 +29,9 @@ module.exports = defineConfig({
     /* Run in headless mode */
     headless: true,
     
-    /* Use system Chrome/Chromium for CachyOS compatibility */
-    channel: 'chromium',
+    /* Use system Chrome/Chromium for CachyOS compatibility (local runs only -
+       CI uses its own Playwright-installed Chromium, see the chromium project below) */
+    ...(process.env.CI ? {} : { channel: 'chromium' }),
 
     /* Extra headers to send with requests */
     extraHTTPHeaders: {
@@ -61,10 +62,14 @@ module.exports = defineConfig({
       name: 'chromium',
       use: {
         ...devices['Desktop Chrome'],
-        // Use system Chromium on CachyOS
-        launchOptions: {
-          executablePath: '/snap/bin/chromium'
-        }
+        // Use system Chromium on CachyOS for local runs. CI installs its own
+        // Chromium via `playwright install` and has no /snap/bin/chromium, so
+        // this override must not apply there.
+        ...(process.env.CI ? {} : {
+          launchOptions: {
+            executablePath: '/snap/bin/chromium'
+          }
+        })
       },
     }
   ],