Rounded-corner window chrome now actually works. The toggle in
Settings > Appearance persists to the window_settings SQLite store and
gates the Tauri window transparency decision at startup, so on next
launch the main window is rebuilt with `transparent: true` and the
border-radius plus edge outline apply without painting white corners.
Flow:
* Toggle in Settings > Appearance -> windowChromeStore saves to
localStorage and calls v2_set_match_system_window_chrome which
writes match_system_window_chrome to window_settings.db.
* Toast reminds the user to restart.
* On next launch, should_use_main_window_transparency() reads the
setting and returns true, Tauri builds the window transparent.
* Setup stores the decision in MAIN_WINDOW_TRANSPARENT. A new command
v2_main_window_is_transparent reports it back to the frontend.
* +page.svelte only applies .app.match-chrome when the window is
actually transparent AND the custom titlebar is visible, so
stale-state toggling never produces white wedges.
* CSS sets html/body transparent via a global class on <html>, then
.app.match-chrome.floating paints the rounded corners plus a
12/28 rgba drop shadow and a 1px darkening outline.
* Maximized state clears the radius automatically.
Env vars QBZ_FORCE_TRANSPARENT_WINDOWS / QBZ_FORCE_OPAQUE_WINDOWS still
take precedence over the DB-persisted toggle.
cc
vicrodh
57e63e3ef5