InputSourceSwitch: Window filter cannot detect some applications

## Problem

Some applications cannot be detected by `hs.window.filter`, making it impossible to automatically switch input sources for these apps.

### Example

Applications like [kitty-quick-access](https://sw.kovidgoyal.net/kitty/kittens/quick-access-terminal/) (a dropdown terminal) don't trigger window filter events when activated.

### Expected Behavior

InputSourceSwitch should be able to switch input source when these applications are activated.

### Current Behavior

No input source switching occurs because the window filter never fires for these applications.