feat(examples-chat): replace sub-LLM dispatch with parent-emits-envel… #713

Job	Run time
Cockpit — build all examples	5m 24s
Cockpit — deploy smoke dry-run	1m 37s
Library — lint / test / build	3m 31s
examples/chat — python smoke	1m 30s
Cockpit — secret-gated integration	1m 26s
Cockpit — representative capability smoke	1m 40s
Cockpit — e2e	3m 14s
Website — lint / build	2m 2s
Website — e2e	3m 11s
Cockpit — build / test	1m 51s
Deploy → Vercel	1m 57s
Production smoke	5m 27s
	32m 50s

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