Adds createAuditErasureHook in core-audit/src/hooks/. The factory returns
a CollectionAfterDeleteHook that calls auditLog.eraseSubject() when a
document is deleted. Defaults to "pseudonymize" mode; coerces numeric ids
to string; skips undefined/null/object ids. Barrel at hooks/index.ts.
6 unit tests cover all guard branches.
Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>
