FSqu: Filesystem-backed job queue

FSqu implements job queues on top of a regular filesystem, where a queue is a directory and each element is a file. Version 1.1.3 is the latest stable release, with no frequent updates. It supports delays/scheduling, at-most-once and at-least-once delivery models, and direct file addition via mv. It is designed for single-machine pipelines that handle large files, and uses the `debug` module for logging. Key differentiators: constant-time operations regardless of queue size, no external dependencies beyond Node.js core modules, and survives process restarts.