macos: add AppleScript commands for text input, key, and mouse events

Add five new AppleScript commands to Ghostty.sdef mirroring the existing
App Intents for terminal input:

- `input text`: send text to a terminal as if pasted
- `send key`: simulate a keyboard event with optional action and modifiers
- `send mouse button`: send a mouse button press/release event
- `send mouse position`: send a mouse cursor position event
- `send mouse scroll`: send a scroll event with precision and momentum

A shared `input action` enumeration (press/release) is used by both key
and mouse button commands. Modifier keys are passed as a comma-separated
string parameter (shift, control, option, command).

macos/Sources/Features/AppleScript/ScriptMouseButtonCommand.swift

@@ -0,0 +1,93 @@
+import AppKit
+
+/// Handler for the `send mouse button` AppleScript command defined in `Ghostty.sdef`.
+///
+/// Cocoa scripting instantiates this class because the command's `<cocoa>` element
+/// specifies `class="GhosttyScriptMouseButtonCommand"`. The runtime calls
+/// `performDefaultImplementation()` to execute the command.
+@MainActor
+@objc(GhosttyScriptMouseButtonCommand)
+final class ScriptMouseButtonCommand: NSScriptCommand {
+    override func performDefaultImplementation() -> Any? {
+        guard let buttonCode = directParameter as? UInt32,
+              let button = ScriptMouseButtonValue(code: buttonCode) else {
+            scriptErrorNumber = errAEParamMissed
+            scriptErrorString = "Missing or unknown mouse button."
+            return nil
+        }
+
+        guard let terminal = evaluatedArguments?["terminal"] as? ScriptTerminal else {
+            scriptErrorNumber = errAEParamMissed
+            scriptErrorString = "Missing terminal target."
+            return nil
+        }
+
+        guard let surfaceView = terminal.surfaceView else {
+            scriptErrorNumber = errAEEventFailed
+            scriptErrorString = "Terminal surface is no longer available."
+            return nil
+        }
+
+        guard let surface = surfaceView.surfaceModel else {
+            scriptErrorNumber = errAEEventFailed
+            scriptErrorString = "Terminal surface model is not available."
+            return nil
+        }
+
+        let action: Ghostty.Input.MouseState
+        if let actionCode = evaluatedArguments?["action"] as? UInt32 {
+            switch actionCode {
+            case "GIpr".fourCharCode: action = .press
+            case "GIrl".fourCharCode: action = .release
+            default: action = .press
+            }
+        } else {
+            action = .press
+        }
+
+        let mods: Ghostty.Input.Mods
+        if let modsString = evaluatedArguments?["modifiers"] as? String {
+            guard let parsed = Ghostty.Input.Mods(scriptModifiers: modsString) else {
+                scriptErrorNumber = errAECoercionFail
+                scriptErrorString = "Unknown modifier in: \(modsString)"
+                return nil
+            }
+            mods = parsed
+        } else {
+            mods = []
+        }
+
+        let mouseEvent = Ghostty.Input.MouseButtonEvent(
+            action: action,
+            button: button.ghosttyButton,
+            mods: mods
+        )
+        surface.sendMouseButton(mouseEvent)
+
+        return nil
+    }
+}
+
+/// Four-character codes matching the `mouse button` enumeration in `Ghostty.sdef`.
+private enum ScriptMouseButtonValue {
+    case left
+    case right
+    case middle
+
+    init?(code: UInt32) {
+        switch code {
+        case "GMlf".fourCharCode: self = .left
+        case "GMrt".fourCharCode: self = .right
+        case "GMmd".fourCharCode: self = .middle
+        default: return nil
+        }
+    }
+
+    var ghosttyButton: Ghostty.Input.MouseButton {
+        switch self {
+        case .left: .left
+        case .right: .right
+        case .middle: .middle
+        }
+    }
+}