[Feature]: Add Cmd+Shift+W shortcut to "Close Window" menu item on macOS

[lukdz]

Summary

In the macOS desktop client, File → Close Window currently has no keyboard accelerator, leaving users with no keyboard shortcut to close the application window.

Adding Cmd+Shift+W (⇧⌘W) to File → Close Window aligns T3 Code with standard macOS Human Interface Guidelines and conventions used by other tabbed desktop applications.

Motivation & Context

In apps/desktop/src/window/DesktopApplicationMenu.ts, the menu definition explicitly notes:

// Cmd/Ctrl+W belongs to the renderer's tab close; it must never close the window.
environment.platform === "darwin"
  ? { label: "Close Window", click: (_item, window) => window?.close() }
  : { role: "quit" },

Because Cmd+W is captured by internal UI surfaces (closing the active terminal split or right-panel tab/diff), users cannot close the window via keyboard at all.

Industry & Platform Precedents

Standard macOS applications that capture Cmd+W for internal tabs or documents consistently map Cmd+Shift+W (⇧⌘W) to close the parent window:

Application	Cmd+W (⌘W)	Cmd+Shift+W (⇧⌘W)
Google Chrome	Close active Tab	Close Window (closes window and all tabs in it)
Apple Safari	Close active Tab	Close Window (closes window and all tabs in it)
Mozilla Firefox	Close active Tab	Close Window (closes window and all tabs in it)
VS Code	Close active Editor tab	Close Window (workbench.action.closeWindow)
Terminal (macOS)	Close active Tab / Pane	Close Window (Shell > Close Window)
iTerm2	Close active Session / Tab	Close Window
Finder	Close active Tab (when multi-tabbed)	Close Window
Obsidian	Close active Tab / Leaf	Close Window
Notion	Close active Tab	Close Window

According to Apple's Human Interface Guidelines (HIG):

• ⌘W: Granular scope (closes active tab/document).
• ⇧⌘W: Container scope (escalates to close the parent window/file).

Proposed Change

In apps/desktop/src/window/DesktopApplicationMenu.ts:

- environment.platform === "darwin"
-   ? { label: "Close Window", click: (_item, window) => window?.close() }
-   : { role: "quit" },
+ environment.platform === "darwin"
+   ? {
+       label: "Close Window",
+       accelerator: "CmdOrCtrl+Shift+W",
+       click: (_item, window) => window?.close(),
+     }
+   : { role: "quit" },