Port the client-side EPUB optimizer from CrossPoint web server to Python. Implements device-specific image optimization (auto-crop, scaling, grayscale conversion, JPEG re-encoding) and EPUB container rewriting (SVG unwrapping, metadata fixes, proper ZIP structure). Supports X3 and X4 device profiles with configurable JPEG quality. Uses Qt's QImage and numpy for image processing with graceful degradation when numpy is unavailable.
