macos: Add AppleScript commands for window and tab control

Add scripting dictionary commands for activating windows, selecting tabs,
closing tabs, and closing windows.

Implement the corresponding Cocoa AppleScript command handlers and expose
minimal ScriptWindow/ScriptTab helpers needed to resolve live targets.

Verified by building Ghostty and running osascript commands against the
absolute Debug app path to exercise all four new commands.

macos/Sources/Features/AppleScript/ScriptFocusCommand.swift

@@ -31,3 +31,49 @@ final class ScriptFocusCommand: NSScriptCommand {
         return nil
     }
 }
+
+/// Handler for the `activate window` AppleScript command defined in `Ghostty.sdef`.
+@MainActor
+@objc(GhosttyScriptActivateWindowCommand)
+final class ScriptActivateWindowCommand: NSScriptCommand {
+    override func performDefaultImplementation() -> Any? {
+        guard let window = evaluatedArguments?["window"] as? ScriptWindow else {
+            scriptErrorNumber = errAEParamMissed
+            scriptErrorString = "Missing window target."
+            return nil
+        }
+
+        guard let targetWindow = window.preferredParentWindow else {
+            scriptErrorNumber = errAEEventFailed
+            scriptErrorString = "Window is no longer available."
+            return nil
+        }
+
+        targetWindow.makeKeyAndOrderFront(nil)
+        NSApp.activate(ignoringOtherApps: true)
+        return nil
+    }
+}
+
+/// Handler for the `select tab` AppleScript command defined in `Ghostty.sdef`.
+@MainActor
+@objc(GhosttyScriptSelectTabCommand)
+final class ScriptSelectTabCommand: NSScriptCommand {
+    override func performDefaultImplementation() -> Any? {
+        guard let tab = evaluatedArguments?["tab"] as? ScriptTab else {
+            scriptErrorNumber = errAEParamMissed
+            scriptErrorString = "Missing tab target."
+            return nil
+        }
+
+        guard let targetWindow = tab.parentWindow else {
+            scriptErrorNumber = errAEEventFailed
+            scriptErrorString = "Tab is no longer available."
+            return nil
+        }
+
+        targetWindow.makeKeyAndOrderFront(nil)
+        NSApp.activate(ignoringOtherApps: true)
+        return nil
+    }
+}