- Add RegionFilter.regionQueryString() to all API calls in renderSubpaths and renderNodesTab
- Add region filtering to /api/analytics/subpaths (filter packets by regional observer hashes)
- Add region filtering to /api/nodes/bulk-health (filter nodes by regional presence)
- Add region filtering to /api/nodes/network-status (filter node counts by region)
- Add region param to nodes lookup in hash collision tab
- Update cache keys to include region param for proper cache separation