Window behavior: close-to-tray + window state

[Hankanman]

Closing the window hides to tray (the poller keeps running; summon via tray/hotkey). Persist/restore window bounds.

[Hankanman]

Status: mostly done. Close-to-tray landed (the window minimizes to the tray when it's up, gated on the tray starting). Remaining: persisting/restoring window size+position across launches. Keeping open for the window-state remainder.