- New /api/dashboard/status endpoint (admin-only, 403 for non-admins)
- Returns server info (uptime, Node version, memory usage)
- Returns polling mode and interval
- Returns cache stats: entry count, total size, per-key breakdown
with item count, size in KB, and TTL remaining
- Status button in admin controls header
- Collapsible status panel with grid layout
- Responsive: single column on mobile
- Add MemoryCache utility with get/set/invalidate/clear
- Cache Sonarr series, Sonarr tags, Radarr movies, Radarr tags
- 60-second TTL - first request fetches, subsequent requests served from cache
- Queue, history, and torrent data remain uncached (changes frequently)
- On cache hit, these 4 heavy API calls resolve instantly
