chore: bump Playwright to 1.64.1 and unpin the browser suite

Playwright supports Ubuntu 26.04 from 1.61.0, so the browser suite can go
back to ubuntu-latest. Raises the floor in package.json as well, because
the old ^1.58.0 still admitted versions that refuse to install on the
image every workflow now runs on. Bundled Chromium moves from 148 to 156.

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

.github/workflows/browser-suite.yml

@@ -21,9 +21,7 @@ permissions:
 jobs:
   browser:
     name: Playwright browser suite
-    # Pinned, not ubuntu-latest: that moved to 26.04 on 2026-11-05 and the locked Playwright 1.60.0
-    # refuses to install there (support starts at 1.61.0). Unpin when Playwright is bumped.
-    runs-on: ubuntu-24.04
+    runs-on: ubuntu-latest
     timeout-minutes: 60
 
     steps: