prototype: layered planning state

[eshulman2]

Stacked on #317.

This PR adds the normalized state foundation for workflows with multiple planning layers:

• artifact lineage, revision, lifecycle, and digest-bound approval metadata
• transitive descendant invalidation when a parent artifact changes
• stale pending work detection while preserving completed work history
• normalized repository, validation, publication, and routing state
• compatibility adapters for legacy planning and repository fields
• resolver support for normalized artifacts and work units

Validation:

• make lint
• focused mypy checks
• 2607 relevant tests passed