desktop_set_window_theme and readThemeSource both checked themeVariant
before themeMode. When UI sends mode='system' with variant='dark' (the
resolved appearance at call time), main pinned nativeTheme.themeSource
to 'dark' — freezing Chromium's prefers-color-scheme and blocking the
renderer's matchMedia listener from reacting to OS theme changes.
Priority now: mode='system' → themeSource='system' (ignore variant).
Variant is only a fallback for callers that omit mode.
Bohdan Triapitsyn
ee9c37bea8