feat: Add base HTML template and implement dashboard, logs, and service views

- Created a base HTML template for consistent layout across pages.
- Developed a dashboard page to display backup service metrics and statuses.
- Implemented a log viewer for detailed log file inspection.
- Added error handling page for better user experience during failures.
- Introduced service detail page to show specific service metrics and actions.
- Enhanced log filtering and viewing capabilities.
- Integrated auto-refresh functionality for real-time updates on metrics.
- Created integration and unit test scripts for backup metrics functionality.

metrics/plex_status.json

@@ -0,0 +1,17 @@
+{
+  "service": "plex",
+  "description": "Plex Media Server backup",
+  "backup_path": "/mnt/share/media/backups/plex",
+  "status": "success",
+  "start_time": "2025-06-18T02:00:00-04:00",
+  "start_timestamp": 1750237200,
+  "end_time": "2025-06-18T02:05:30-04:00",
+  "end_timestamp": 1750237530,
+  "duration_seconds": 330,
+  "current_operation": "Completed",
+  "files_processed": 3,
+  "total_size_bytes": 1073741824,
+  "message": "Backup completed successfully",
+  "last_updated": "2025-06-18T02:05:30-04:00",
+  "hostname": "book"
+}