e2e-windows hangs in :e2e-desktop:run and times out after 45 min #54

The e2e-windows job in pr-build-check.yml has not passed in any of the last 40 workflow runs — it is either cancelled by concurrency or times out. It is not a regression from a recent PR; #52 and #53 both hit it while every other platform stayed green.

On the two most recent runs the job reaches :e2e-desktop:run and then produces no suite output at all until the 45-minute timeout kills it:

2026-08-09T05:30:53Z  > Task :e2e-desktop:run
2026-08-09T06:12:22Z  Terminate batch job (Y/N)?
2026-08-09T06:12:23Z  ##[error]The operation was canceled.

Compare with e2e-linux (1 m 54 s) and e2e-macos (1 m 2 s) on the same runs, and a local macOS run which finishes in 26 s with SUITE_FINISHED passed=true. So the suite is hanging at startup on the WebView2 runner rather than failing a case — most likely Tao window creation or WebView2 runtime initialisation never completing on a headless windows-latest runner.

Worth checking:

• whether the WebView2 Runtime is actually present on the runner image (the job only verifies compose_webview_windows.dll + WebView2Loader.dll are downloaded, not that the runtime is installed)
• adding a watchdog to VisualSuiteApp so the suite fails fast with a diagnostic instead of burning 45 minutes
• capturing a thread dump before the timeout

Windows is a supported desktop target, so this job is currently providing no coverage for it.