feat(auditor): waive_finding verb + findings queue panel

Wire the long-unwired mark_waived repo method to a new auditor-only
flow verb waive_finding, severity-scoped to minor/nit (blocker/major
must be fixed, never waived), requiring a note, with a task.finding_waived
audit event and no task status change. Add the verb to the IntentSpec
table (auto-derived into the auditor manifest), the flow_auditor route,
and the flow_server MCP tool.

Surface open review findings (cross-task, blocking-first) on the
auditor dashboard via ReviewFindingsRepository.list_open_findings and a
new findings field on AuditorDashboard. Restore the panel's 4-card
auditor layout with a new read-only FindingsQueuePanel as the 4th card.

panel/src/lib/mock-data.ts

@@ -1187,6 +1187,7 @@ export const mockAuditorDashboard = {
     },
   ],
   recent_reports: mockAuditorReports,
+  findings: [],
 };
 
 // Mock mode: dev = mock, production = real backend