Summary
• Added stable, descending sort to `GetAnnouncements()` so that the API always returns the latest announcements first.
• Introduced helper `getPublishTime()` to safely parse `publishDate` (RFC 3339) and fall back to zero value on failure.
• Switched to `sort.SliceStable` for deterministic ordering when timestamps are identical.
• Imported the standard `sort` package and removed redundant, duplicate date parsing.
Impact
Front-end no longer needs to perform client-side sorting; the latest announcement is guaranteed to appear at the top on all platforms and clients.
