Stabilize WebKit release gate

[sonson0910]

Summary

• activate the rating button through its native keyboard path in the long WebKit learning journey
• preserve the 60-second fail-fast timeout and all transition assertions

Evidence

• release candidate run 33304180465 reproduced the pointer actionability timeout twice; retry passed both times
• targeted WebKit journey passes 3/3 with the keyboard activation

Test plan

• CI=true playwright test e2e/phase5-learning.spec.ts --project=webkit --grep "Today is the default four-part shell" --repeat-each=3 --workers=1
• GitHub quality gates