test: use happy dom (#34154)

web/app/components/plugins/plugin-detail-panel/__tests__/endpoint-card.spec.tsx

@@ -142,7 +142,7 @@ describe('EndpointCard', () => {
     failureFlags.disable = false
     failureFlags.delete = false
     failureFlags.update = false
-    // Polyfill document.execCommand for copy-to-clipboard in jsdom
+    // Polyfill document.execCommand for copy-to-clipboard in the test DOM runtime
     if (typeof document.execCommand !== 'function') {
       document.execCommand = vi.fn().mockReturnValue(true)
     }

web/app/components/plugins/plugin-detail-panel/subscription-list/create/__tests__/oauth-client.spec.tsx

@@ -102,10 +102,12 @@ vi.mock('@/app/components/base/ui/toast', () => ({
 }))
 
 const mockClipboardWriteText = vi.fn()
-Object.assign(navigator, {
-  clipboard: {
+Object.defineProperty(navigator, 'clipboard', {
+  value: {
     writeText: mockClipboardWriteText,
   },
+  configurable: true,
+  writable: true,
 })
 
 vi.mock('@/app/components/base/modal/modal', () => ({
@@ -192,6 +194,13 @@ describe('OAuthClientSettingsModal', () => {
     vi.clearAllMocks()
     mockUsePluginStore.mockReturnValue(mockPluginDetail)
     mockClipboardWriteText.mockResolvedValue(undefined)
+    Object.defineProperty(navigator, 'clipboard', {
+      value: {
+        writeText: mockClipboardWriteText,
+      },
+      configurable: true,
+      writable: true,
+    })
     setMockFormValues({
       values: { client_id: 'test-client-id', client_secret: 'test-client-secret' },
       isCheckValidated: true,