💄 Use primary monitor instead of current (#32)

IMO current_monitor is a bit misleading as it uses the current monitor
the app is in, not the current monitor the user interacts with.

This is not optimal in a multi-monitor setup, as you often end
up with spyglass on the monitor that is not your primary. primary_monitor
on the other hand uses, you guessed it, the primary monitor, which I
see as more logical.

The optimal solution would be to get the monitor that the user is
currently interacting with, but this is not trivial.

crates/tauri/src/window.rs

@@ -3,7 +3,7 @@ use tauri::{async_runtime::spawn, LogicalSize, Size, Window};
 use crate::{cmd, constants};
 
 pub fn center_window(window: &Window) {
-    if let Some(monitor) = window.current_monitor().unwrap() {
+    if let Some(monitor) = window.primary_monitor().unwrap() {
         let size = monitor.size();
         let scale = monitor.scale_factor();