feat: complete offline digestion and privacy controls

[karngyan]

Summary

• add autophagy digest and patterns with inspectable Evidence Packet output and explicit no-model/no-network reporting
• enforce default secret redaction and repeatable project/artifact path exclusions before persistence
• scope native cursors by project, exclusion set, and privacy-policy version
• add canonical AEP JSONL export, transactional retention preview/apply, session deletion, and guarded delete-all
• hash default source paths, add a runnable mise run demo, and document the Milestone 1 threat model and residual risks

Verification

• mise run check
• mise run demo
• end-to-end CLI: 11 events -> 2 findings -> digest -> export -> delete/prune
• privacy fixture: 1 secret redacted, 1 private path excluded, exported secret absent
• retention dry-run leaves state unchanged; delete-all requires --confirm delete-all