New node: Validate files against templates

A new Validate Files node brings flexible, template-based validation directly into your Multi FileFeed workflows. You can validate one or multiple files against their respective templates at any point in your flow, making it easier to enforce data quality exactly where you need it.
Validation results are clearly surfaced, with failures showing error summaries and easy access to file previews for troubleshooting. This node also provides a modular alternative to built-in validation, giving you more control over how and when validation is applied within your workflows.