feat: add owner audit log

[darwin67]

Summary

• add an owner-only organization audit-log LiveView with actor, target, timestamp, and action context
• snapshot actor, target, and workspace labels so later account changes or deletion do not rewrite history, with immutable ID fallbacks for legacy events
• add cursor-based pagination and reauthorize owners on every page fetch, concealing events after access revocation
• expose semantic active audit-log navigation on desktop and mobile while hiding it from non-owners
• cover rendering, immutable and legacy labels, equal-timestamp pagination boundaries, authentication, authorization, revoked access, stale roles, and responsive navigation

Verification

• mix precommit (445 tests passed)
• mix assets.build
• focused audit/context/API suite (74 tests passed)
• browser verification at 390px: snapshot labels render, More is active, and there is no horizontal overflow or bottom-navigation overlap