Automatically migrates legacy template syntax to modern template: syntax:
- Scans all YAML files for platform: template definitions
- Converts sensors and binary_sensors to modern format
- Creates timestamped backups
- Removes legacy definitions
- Adds modern template: section to configuration.yaml
- Preserves all template features (icons, attributes, device_class, etc)
- Generates restore script for rollback
Fixes all 67 template deprecation warnings automatically.
