fix(app): reveal workspace-jump numbers only for the active modifier (#1580)

Holding the workspace-jump modifier reveals numbered badges in the sidebar for jumping to a workspace (Cmd+1..9). On the desktop app the badges also appeared while holding Option or Control, neither of which performs the jump — only Cmd does on macOS desktop (Ctrl on non-Mac, Alt on web).

The keydown/keyup handler flagged badge visibility for Alt on every runtime and for both Meta and Control on desktop — broader than the active workspace.navigate.index binding. Gate the badges to the single modifier that performs the jump on the current runtime, via a new getWorkspaceIndexJumpModifierKey helper. Adds unit tests for the three runtime cases.

Co-authored-by: Claude Opus 4.8 <noreply@anthropic.com>

packages/app/src/keyboard/keyboard-shortcuts.test.ts

@@ -3,6 +3,7 @@ import {
   buildKeyboardShortcutHelpSections,
   buildEffectiveBindings,
   getBindingIdForAction,
+  getWorkspaceIndexJumpModifierKey,
   resolveKeyboardShortcut,
   type ChordState,
   type KeyboardShortcutContext,
@@ -638,3 +639,18 @@ describe("keyboard-shortcut help sections", () => {
     ).toBeNull();
   });
 });
+
+describe("getWorkspaceIndexJumpModifierKey", () => {
+  it("uses Alt on web, regardless of OS", () => {
+    expect(getWorkspaceIndexJumpModifierKey({ isMac: true, isDesktop: false })).toBe("Alt");
+    expect(getWorkspaceIndexJumpModifierKey({ isMac: false, isDesktop: false })).toBe("Alt");
+  });
+
+  it("uses Cmd (Meta) on desktop Mac, not Control or Alt", () => {
+    expect(getWorkspaceIndexJumpModifierKey({ isMac: true, isDesktop: true })).toBe("Meta");
+  });
+
+  it("uses Ctrl on desktop non-Mac, not Meta or Alt", () => {
+    expect(getWorkspaceIndexJumpModifierKey({ isMac: false, isDesktop: true })).toBe("Control");
+  });
+});