String List Editor

Create and edit a list of strings with UI support for adding items and drag & drop of files. UI behavior (frontend): - A multiline text area representing one string per line. - An 'Add' button appends a new empty line. - A drop zone: dropping files appends their full path(s) as new lines. Backend behavior: - Splits the multiline text into a list of strings (one per non-empty line, trimming whitespace). - Returns a new list (non-mutating).