nebula-mesh: GET /api/v1/audit-log discloses all entries to any operator

internal/api/audit.go:12 — handleGetAuditLog does no admin check. The route is bearer-auth gated only; any operator API key returns the full audit log via store.ListAuditEntries up to limit=1000. This includes cross-tenant actor names, host/CA/operator IDs, action timestamps, and masked-IP entrie...