fix: improve window "spotlight"-ness

[cablehead]

Stacks' makes a bunch of platform calls to configure its window as a spotlight-like window: https://github.com/cablehead/stacks/blob/main/src-tauri/src/spotlight.rs -- it'd be nicer if this was in native Swift.

https://github.com/Brendonovich/swift-rs

h/t @arn4v for the link.

The main window doesn't quite behave as well as the native macOS spotlight. As an example, when the last window in a macOS space closes, macOS will focus the previous space. If Stacks' is the only window in a space, this results in the current space annoyingly losing focus as you activate and deactivate Stacks. Hopefully there's a macOS API to say: "don't count this window towards the count of windows in a space.

Potentially helpful:

https://github.com/ahkohd/tauri-nspanel

[slidingshade]

Also stacks window don't pop up if your current app in full-screen mode..