cloud-sync now ships a real Qt UI alongside the tkinter fallback.
Architecture:
- HeadlessProgress: --no-gui path, plain stdout
- TkProgressWindow: stdlib fallback when Qt isn't installed
- QtProgressWindow: preferred path; supports both PySide6 and PyQt6
(interchangeable APIs for our subset)
The factory in ui.py picks Qt → tkinter → headless. Tk stays so the
zipapp still works on bare Python with no extras.
Threading: QApplication runs on the main thread (started by run_with
via QDialog.exec). The restic worker runs on a daemon threading.Thread.
Cross-thread UI updates go via a Signal on a bridge QObject so Qt
auto-marshals them onto the main thread via a queued connection.
Cancellation: WM close + Cancel button both set a flag. sync.pull/push
pass ui.is_cancelled as restic.run's cancel_check; the subprocess gets
killed and returns -1 → exit 1.
Theme: Fusion style + Prism's dark palette (RGB values copied as facts
from PrismLauncher's DarkTheme.cpp). Override with PRISM_THEME=off.
Pyz size went 20 KB → 36 KB (added ui.py + ui_qt.py).
33 tests still green.
