There's probably a bunch of work here, but we can get started on all of it by moving Audit to ApplicationSearch. In general:

• Audit has two views now. One queries audits, the other queries commits by audit status. I think we should basically throw out the audit view and make all the queries return commits. To find relevant audits, you're searching for commits which have some relevant audit state or auditors. Particularly, searching by audit can currently show the same commit multiple times (if it has multiple auditors) which is fairly confusing.
• Broadly, this means PhabricatorAuditQuery should do less, and probably lose some methods. It should also become PolicyAware. It's possible it should be removed entirely, and just become a needAudits() or similar.
• PhabricatorAuditCommitQuery should merge into DiffusionCommitQuery and eventually die.
• We'll end up with a single, cohesive ApplicationSearch view with some default queries like "Need Attention" (commits with open audits the viewer is responsible for), "Open Audits" (commits with open audits) and "All Commits" (commits with no other filters) that is simpler and more powerful than the whole mess we have now.