macOS: fix tab context menu opens on macOS 26 with titlebar tabs (#9831)

Description:
Context menu works on tabs with titlebar-style=tabs on MacOS Tahoe 26

Closes #9817 

Demo:


https://github.com/user-attachments/assets/60eaae6e-a3ff-41eb-8c86-ba700490d6e2



Note:
- Tried first a passthrough-views approach, but AppKit’s internal
toolbar subviews continued intercepting right-clicks.
- Runtime subclassing proposed by Claude also worked but was rejected as
too fragile.
- Final solution routes secondary-click events at the window level using
sendEvent(_:), forwarding them to the tab bar only when the click is
visually within its bounds.

AI Disclosure:
AI (Claude Code and Codex) assisted with early explorations, but final
implementation was developed manually after evaluating and discarding
the unsafe subclassing approach proposed by Claude.

macos/Sources/Features/Terminal/Window Styles/TitlebarTabsTahoeTerminalWindow.swift

@@ -67,6 +67,38 @@ class TitlebarTabsTahoeTerminalWindow: TransparentTitlebarTerminalWindow, NSTool
         
         viewModel.isMainWindow = false
     }
+
+    /// On our Tahoe titlebar tabs, we need to fix up right click events because they don't work
+    /// naturally due to whatever mess we made.
+    override func sendEvent(_ event: NSEvent) {
+        guard viewModel.hasTabBar else {
+            super.sendEvent(event)
+            return
+        }
+
+        let isRightClick =
+            event.type == .rightMouseDown ||
+            (event.type == .otherMouseDown && event.buttonNumber == 2) ||
+            (event.type == .leftMouseDown && event.modifierFlags.contains(.control))
+        guard isRightClick else {
+            super.sendEvent(event)
+            return
+        }
+        
+        guard let tabBarView = findTabBar() else {
+            super.sendEvent(event)
+            return
+        }
+        
+        let locationInTabBar = tabBarView.convert(event.locationInWindow, from: nil)
+        guard tabBarView.bounds.contains(locationInTabBar) else {
+            super.sendEvent(event)
+            return
+        }
+        
+        tabBarView.rightMouseDown(with: event)
+    }
+
     // This is called by macOS for native tabbing in order to add the tab bar. We hook into
     // this, detect the tab bar being added, and override its behavior.
     override func addTitlebarAccessoryViewController(_ childViewController: NSTitlebarAccessoryViewController) {