feat(a2ui): align validation with v0.9 CheckRule spec #317

Job	Run time
Cockpit — e2e	1m 47s
Cockpit — representative capability smoke	1m 10s
Website — lint / build	1m 45s
Cockpit — secret-gated integration	1m 6s
Cockpit — deploy smoke dry-run	1m 9s
Library — lint / test / build	1m 19s
Chat Agent — smoke	1m 18s
Cockpit — build all examples	5m 6s
Website — e2e	2m 17s
Cockpit — build / test	1m 26s
Deploy → Vercel	0s
Production smoke	0s
	18m 23s

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