macos: prevent moveFocus from being an infinite loop (#2905)

Fixes #2900

It's possible for moveFocus to infinite loop if the surface view we're
trying to move focus to NEVER gets attached to a window. This can happen
if the window is destroyed.

I think this issue should be more systemically fixed so it can't happen
but this workaround for now prevents moveFocus from being an infinite
loop source for the time being.

macos/Sources/Ghostty/Ghostty.TerminalSplit.swift

@@ -429,12 +429,34 @@ extension Ghostty {
     /// will lose focus. There has to be some nice SwiftUI-native way to fix this but I can't
     /// figure it out so we're going to do this hacky thing to bring focus back to the terminal
     /// that should have it.
-    static func moveFocus(to: SurfaceView, from: SurfaceView? = nil) {
-        DispatchQueue.main.async {
+    static func moveFocus(
+        to: SurfaceView,
+        from: SurfaceView? = nil,
+        delay: TimeInterval? = nil
+    ) {
+        // The whole delay machinery is a bit of a hack to work around a
+        // situation where the window is destroyed and the surface view
+        // will never be attached to a window. Realistically, we should
+        // handle this upstream but we also don't want this function to be
+        // a source of infinite loops.
+
+        // Our max delay before we give up
+        let maxDelay: TimeInterval = 0.5
+        guard (delay ?? 0) < maxDelay else { return }
+
+        // We start at a 50 millisecond delay and do a doubling backoff
+        let nextDelay: TimeInterval = if let delay {
+            delay * 2
+        } else {
+            // 100 milliseconds
+            0.05
+        }
+
+        let work: DispatchWorkItem = .init {
             // If the callback runs before the surface is attached to a view
             // then the window will be nil. We just reschedule in that case.
             guard let window = to.window else {
-                moveFocus(to: to, from: from)
+                moveFocus(to: to, from: from, delay: nextDelay)
                 return
             }
 
@@ -448,5 +470,12 @@ extension Ghostty {
 
             window.makeFirstResponder(to)
         }
+
+        let queue = DispatchQueue.main
+        if let delay {
+            queue.asyncAfter(deadline: .now() + delay, execute: work)
+        } else {
+            queue.async(execute: work)
+        }
     }
 }