9b748db4d4
Move the valid filename regex pattern to a shared constant in `app/utils/filename_utils.py` and update both the task logic and security tests to use it. This eliminates duplication and ensures consistency across the codebase. Also normalized line endings to LF in affected files to ensure CI compatibility. Co-authored-by: christianlouis <361235+christianlouis@users.noreply.github.com>