feat: Gradio Custom Component for NiiVue (#29)

fix(ui): prediction overlay invisible, race condition, thread safety (#23) (#23)

style: format test_app.py for CI (line length)

fix(ui): replace base64 data URLs with Gradio file serving (#19)

fix(ui): lazy dataset loading to prevent HF Spaces timeout (#14)

fix(pipeline): copy input files to results_dir and add UI cleanup

feat(phase-4): Gradio UI with NiiVue visualization (#5)