Function CheckProductionRules

Pure pre-render production checks that validate rules the headless browser worker does not inspect:

• Provenance / 'Error': any Assets.Approved with Provenance === 'Generated' missing Generation (or missing ModelID, PromptRunID, or Prompt)
• Provenance / 'Error': sum of Generation.DurationSeconds across generated Video assets exceeding settings.MaxGeneratedVideoSeconds
• Audio / 'Error': any narration line in Audio.Narration.Script missing AudioFileID
• Audio / 'Error': Audio.Music.AssetKey is set and the matching asset in Assets.Approved is missing or has no StagedPath