ci: point storyboard runner at @adcp/sdk latest instead of adcp-3.1 #2034

Job	Run time
AdCP storyboard runner — sales-proposal-mode (proposal_finalize)	1m 50s
v3 reference seller — pytest (respx-mocked upstream)	43s
AdCP storyboard runner — v3 reference seller (translator)	2m 39s
Downstream import smoke (representative consumer symbols)	37s
AdCP storyboard runner — examples/seller_agent.py (@adcp/sdk latest)	2m 47s
Validate schemas are up-to-date	20m 56s
AdCP storyboard runner — examples/multi_platform_seller (PlatformRouter)	1m 58s
Postgres conformance tests (Postgres 16)	1m 24s
Validate conventional commit format	12s
Test Python 3.12	5m 55s
Test Python 3.13	6m 3s
Test Python 3.11	6m 57s
Test Python 3.10	6m 57s
AdCP storyboard runner — examples/seller_agent.py	4s
	59m 2s

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