feat(logs): cluster-wide log file download

[wezell]

Summary

• Adds new _downloadClusterLog REST endpoint that downloads a log file from all cluster nodes and returns them as a single ZIP archive
• Each node's log is prefixed with a short server ID and hostname for easy identification
• Inter-node communication supports HTTPS with fall back to HTTP
• Adds a Dojo dialog to the log viewer UI letting users choose between downloading from this server or all cluster nodes
• Makes the log viewer panel fill the full viewport height

Changes

• ClusterLogCollector.java (new): Parallel HTTP/HTTPS fetcher that collects logs from peer servers, assembles them into a ZIP with an _errors.txt for any failures
• MaintenanceResource.java: New _downloadClusterLog/{fileName} endpoint with short-lived JWT token for peer authentication
• tail_log.jsp: Download button now opens a dialog with "This Server" / "All Cluster Nodes" options; log viewer fills viewport
• Language.properties: New i18n keys for the download dialog
• ClusterLogCollectorTest.java (new): Integration tests covering ZIP assembly, label formatting, error handling, and peer skip logic

Test plan

• Integration tests pass: ClusterLogCollectorTest (6 tests)
• Manual test: single-node download still works via dialog
• Manual test: cluster download returns ZIP with logs from all nodes
• Manual test: cluster download with unreachable node includes _errors.txt
• Manual test: log viewer fills full viewport height

🤖 Generated with Claude Code

This PR fixes: #34806