Draft: Resolve "Batch Transform Feature Implementation Plan"

Merge Request 15-batch-transform-feature-implementation-plan into main

Batch Transformation Feature Added

This change adds a new /batch-transform route that allows users to transform multiple text inputs at once. Users can upload multiple .txt files (up to 5MB each) or enter text directly into the form. The system applies one of several transformations (NATO phonetic alphabet conversion, uppercase conversion, or SHA-256 hashing) to each input and displays the results. The implementation includes proper validation for file types, sizes, and content, with appropriate error handling for invalid inputs. This feature enhances the application by enabling bulk processing rather than requiring users to transform text one piece at a time.

Relates to #15