Feature/Fix: Add a reversible lineage accounting selector

[iam-brain]

Summary

• add internal legacy, shadow, and lineage accounting modes with legacy as the default
• isolate caches by accounting mode and schema for safe rollback/rebuild
• run shadow and lineage through the two-pass scanner with debug-only diagnostics
• combine primary ledger rows with permanent family-scoped containment without double counting
• fail lineage mode closed before cache publication when evidence is incomplete or cancellation occurs

Closes #19

Validation

• swift test --jobs 4 --filter CodexLineageAccountingSelectorTests (7 passed)
• make check
• env SDKROOT=/Applications/Xcode.app/Contents/Developer/Platforms/MacOSX.platform/Developer/SDKs/MacOSX26.5.sdk make test (54 groups, no failures or retries)