CBG-4429: Audit with CV as doc version where possible

[bbrks]

CBG-4429

Some cases aren't possible to use CV (i.e. attachments being written before the document has been written - reliant on CAS macro expansion to determine CV) - they are kept as RevTree IDs with a comment explaining why. This is considered a known-issue that we may not fix.

Integration Tests

• GSI=true,xattrs=true https://jenkins.sgwdev.com/job/SyncGatewayIntegration/62/

[Copilot]

Pull Request Overview

This PR updates audit logging to use Current Version (CV) as the document version where possible, improving consistency with the new version vector approach. The changes address CBG-4429 by preferring CV over RevTreeID in audit events while maintaining backwards compatibility.

Key changes:

• Introduces CVOrRevTreeID() helper methods that prefer CV but fallback to RevTreeID
• Updates audit logging calls to use CV where the document state is available
• Maintains RevTreeID usage for attachment events where CV is not yet determined

Reviewed Changes

Copilot reviewed 4 out of 4 changed files in this pull request and generated 1 comment.

File	Description
db/document.go	Adds CVOrRevTreeID() helper methods for SyncData and DocVersion structs
db/database.go	Updates document resync audit to use CV when available
db/crud.go	Updates document update/delete audit events to use CV, keeps RevTreeID for attachment events with explanatory comment
rest/audit_test.go	Updates test assertions to use CV, fixes require.Equal parameter order, and removes HLV skip condition