macos: handle multiple monitors properly

macos/Sources/Features/QuickTerminal/QuickTerminalScreen.swift

@@ -0,0 +1,37 @@
+import Cocoa
+
+enum QuickTerminalScreen {
+    case main
+    case mouse
+    case menuBar
+
+    init?(fromGhosttyConfig string: String) {
+        switch (string) {
+        case "main":
+            self = .main
+
+        case "mouse":
+            self = .mouse
+            
+        case "macos-menu-bar":
+            self = .menuBar
+            
+        default:
+            return nil
+        }
+    }
+
+    var screen: NSScreen? {
+        switch (self) {
+        case .main:
+            return NSScreen.main
+
+        case .mouse:
+            let mouseLoc = NSEvent.mouseLocation
+            return NSScreen.screens.first(where: { $0.frame.contains(mouseLoc) })
+
+        case .menuBar:
+            return NSScreen.screens.first
+        }
+    }
+}