feat(audit): add download button in hermes audit

[LeoZhangZXZ]

Motivation

Audit log consumers sometimes need to export event data for offline analysis, compliance reporting, or sharing with other teams. Previously there was no way to download the currently filtered audit events — users had to rely on the API directly or manually copy data from the UI.

What Changed

• Added a downloadEvents Redux action that calls /events/download with the current filters (search term, time range, active attribute filters) and triggers a browser file download of the result as audit-events.json
• Added a Download all button to the audit event list toolbar, showing a count of matching events and a loading spinner while the download is in progress
• Wired up the new action through the Redux container to the list component

Usage

Apply filters and/or a time range as usual in the audit UI, then click Download all (N) in the toolbar. The browser will download audit-events.json containing all matching events. The button is disabled while a fetch or download is already in progress.