Storyboard coverage: creative lifecycle

[bokelley]

Add a creative_lifecycle.yaml compliance storyboard covering:

• Sync multiple creatives
• List with/without snapshot
• Build and preview across formats
• Creative status transitions

The existing creative storyboards cover individual operations but not the full lifecycle with multiple formats.

Discovered in #424.

[bokelley]

Done in adcontextprotocol/adcp#1985. Added creative_lifecycle.yaml covering multi-format sync (display, video, native), list with filtering, build and preview across formats. Added creative_lifecycle to the creative compliance track.