fix: close other open toolbar menus when a menu button is clicked

The toggle button used @click.stop, which halted the click before it
reached the document-level outside-click listeners. As a result, opening
one dropdown (e.g. export) left a previously-opened dropdown (e.g.
generate) still open. The containment check in handleDocumentClick
already prevents a toggle's own opening click from self-closing, so
.stop was unnecessary; removing it lets sibling menus close on outside
click as intended.

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>

src/components/ToolbarMenuButton.test.ts

@@ -69,4 +69,21 @@ describe('ToolbarMenuButton', () => {
     expect(wrapper.find('[data-testid="item-a"]').exists()).toBe(false)
     wrapper.unmount()
   })
+
+  it('closes an open menu when another menu button is clicked', async () => {
+    const first = mountMenu({ label: '生成 ▾', toggleTestid: 'generate-menu-toggle' })
+    const second = mountMenu({ label: '导出 ▾', toggleTestid: 'export-menu-toggle' })
+
+    await first.get('button[data-testid="generate-menu-toggle"]').trigger('click')
+    expect(first.find('[data-testid="item-a"]').exists()).toBe(true)
+
+    await second.get('button[data-testid="export-menu-toggle"]').trigger('click')
+    await first.vm.$nextTick()
+
+    expect(second.find('[data-testid="item-a"]').exists()).toBe(true)
+    expect(first.find('[data-testid="item-a"]').exists()).toBe(false)
+
+    first.unmount()
+    second.unmount()
+  })
 })

src/components/ToolbarMenuButton.vue

@@ -47,7 +47,7 @@ onUnmounted(() => {
       :data-testid="toggleTestid"
       :disabled="disabled"
       :aria-expanded="open"
-      @click.stop="toggle"
+      @click="toggle"
     >
       {{ label }}
     </button>