fix: quote multi-word role value in Linux smoke test selector

The selector parser tokenizes on whitespace, so `role=push button`
was split into two tokens causing a parse failure. Use single quotes
inside the selector: `role='push button'`.

https://claude.ai/code/session_01H9hrmueNF5pcBM8JeX81mT

Author: claude

test/integration/replays/linux/01-desktop-smoke.ad

@@ -6,5 +6,5 @@ open gnome-calculator
 wait 3000
 screenshot "./test/screenshots/replays/linux-calculator.png"
 snapshot
-is exists "label=Calculator || label=calculator || appName=gnome-calculator || appName=Calculator || role=push button"
+is exists "label=Calculator || label=calculator || appName=gnome-calculator || appName=Calculator || role='push button'"
 snapshot -i