Generated-policy editor: drafts, autosave, and audit history

Delete an unpublished generated policy draft. Admins can now delete a draft generated policy from the editor before publishing, so unwanted drafts don't clutter the Policies overview.

Persistent autosave status in the policy editor. The generated-policy editor now shows a persistent autosave indicator next to the generation date so admins always know their edits are safely saved.

Audit log timeline for all policies. Every policy, whether uploaded or AI-generated, now has an audit log timeline showing every generation, edit, publish, acknowledgement, and reassignment in one chronological view, giving auditors a complete history of who did what and when.