macos: expose name (title) on window, tab, and terminal via AppleScript

Add a `name` property (code `pnam`, cocoa key `title`) to the window, tab,
and terminal classes in the scripting definition. This follows the standard
Cocoa scripting convention where `name`/`pnam` maps to the `title` KVC key,
matching what Apple does in CocoaStandard.sdef for NSWindow.

Also fixes the pre-existing terminal `title` property which used a custom
four-char code (`Gttl`) that AppleScript could not resolve directly — only
via `properties of terminal`. All three classes now use the standard `pnam`
code so `name of window 1`, `name of tab 1 of window 1`, and
`name of terminal 1` all work correctly.

macos/Sources/Features/AppleScript/ScriptTab.swift

@@ -37,6 +37,14 @@ final class ScriptTab: NSObject {
         stableID
     }
 
+    /// Exposed as the AppleScript `title` property.
+    ///
+    /// Returns the title of the tab's window.
+    @objc(title)
+    var title: String {
+        controller?.window?.title ?? ""
+    }
+
     /// Exposed as the AppleScript `index` property.
     ///
     /// Cocoa scripting expects this to be 1-based for user-facing collections.