Desktop: remember window size, position, and maximized state

[rebaserHEAD]

The window opens at a hardcoded 1600x1000 every launch (main.cjs createWindow). Standard desktop behavior is to restore where you left it.

• Persist bounds + maximized on close; restore on launch (guard against off-screen bounds after monitor changes).
• Note: the settings store''s settings.json is renderer-owned and loads after window creation, so main either reads the file directly at startup or keeps a small separate window-state file. Either is fine; don''t block window creation on IPC.

[rebaserHEAD]

Worth including in the persisted window state: the interface zoom level (the menu exposes zoomIn/zoomOut/reset roles, but the factor resets every launch).