Fix auth cookie name (arm_token) + separate Run All from suite count

1. The driver set cookie name 'token' but the server uses 'arm_token',
   so Playwright always saw the login page instead of the surface.

2. Split "Run All (N suites)" into a "Run All" button + separate
   suite count label — count changes over time and shouldn't be
   part of the button text.

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

ci/surface-test-driver.js

@@ -33,9 +33,9 @@ if (!TOKEN) {
   const browser = await chromium.launch({ headless: true });
   const context = await browser.newContext();
 
-  // Set auth cookie/token
+  // Set auth cookie — name must match server's SetCookie ("arm_token")
   await context.addCookies([{
-    name: 'token',
+    name: 'arm_token',
     value: TOKEN,
     domain: new URL(SERVER).hostname,
     path: '/',