docs(chat): explain the dual ensureChatRootStyles path (unblocks demo redeploy) #984

Job	Run time
Cockpit — build all examples	5m 13s
Cockpit — deploy smoke dry-run	1m 8s
Website — lint / build	1m 44s
Cockpit — representative capability smoke	1m 14s
Cockpit — secret-gated integration	1m 0s
Cockpit — build / test	1m 37s
Library — lint / test / build	3m 31s
Website — e2e	2m 28s
PostHog — dashboards-as-code drift check	1m 9s
examples/chat — aimock e2e	2m 30s
Cockpit — e2e	3m 3s
examples/chat — python smoke	1m 30s
Deploy → Vercel	0s
Production smoke	-1s
	26m 6s

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