feat: Enhance Notifications feature with accessibility improvements and test remediation

- Added aria-label attributes to buttons in Notifications component for better accessibility.
- Updated Notifications tests to use new button interactions and ensure proper functionality.
- Refactored notifications payload tests to mock API responses and validate payload transformations.
- Improved error handling and feedback in notification provider tests.
- Adjusted Telegram notification provider tests to streamline edit interactions.

frontend/src/pages/Notifications.tsx

@@ -703,12 +703,13 @@ const Notifications: FC = () => {
                       onClick={() => testMutation.mutate({ ...provider, type: normalizeProviderType(provider.type) })}
                       isLoading={testMutation.isPending}
                       title={t('notificationProviders.sendTest')}
+                      aria-label={t('notificationProviders.sendTest')}
                     >
                       <Send className="w-4 h-4" />
                     </Button>
                   )}
                   {!isUnsupportedProviderType(provider.type) && (
-                    <Button variant="secondary" size="sm" onClick={() => setEditingId(provider.id)}>
+                    <Button variant="secondary" size="sm" onClick={() => setEditingId(provider.id)} aria-label={t('common.edit')}>
                       <Edit2 className="w-4 h-4" />
                     </Button>
                   )}
@@ -718,6 +719,7 @@ const Notifications: FC = () => {
                     onClick={() => {
                       if (confirm(t('notificationProviders.deleteConfirm'))) deleteMutation.mutate(provider.id);
                     }}
+                    aria-label={t('common.delete')}
                   >
                     <Trash2 className="w-4 h-4" />
                   </Button>

frontend/src/pages/__tests__/Notifications.test.tsx

@@ -446,13 +446,13 @@ describe('Notifications', () => {
 
   it('submits provider test action from form using normalized discord type', async () => {
     vi.mocked(notificationsApi.testProvider).mockResolvedValue()
+    setupMocks([baseProvider])
 
     const user = userEvent.setup()
     renderWithQueryClient(<Notifications />)
 
-    await user.click(await screen.findByTestId('add-provider-btn'))
-    await user.type(screen.getByTestId('provider-name'), 'Preview/Test Provider')
-    await user.type(screen.getByTestId('provider-url'), 'https://example.com/webhook')
+    const row = await screen.findByTestId(`provider-row-${baseProvider.id}`)
+    await user.click(within(row).getByRole('button', { name: /edit/i }))
 
     await user.click(screen.getByTestId('provider-test-btn'))
 
@@ -568,13 +568,14 @@ describe('Notifications', () => {
 
   it('shows error toast when test mutation fails', async () => {
     vi.mocked(notificationsApi.testProvider).mockRejectedValue(new Error('Connection refused'))
+    setupMocks([baseProvider])
 
     const user = userEvent.setup()
     renderWithQueryClient(<Notifications />)
 
-    await user.click(await screen.findByTestId('add-provider-btn'))
-    await user.type(screen.getByTestId('provider-name'), 'Failing Provider')
-    await user.type(screen.getByTestId('provider-url'), 'https://example.com/webhook')
+    const row = await screen.findByTestId(`provider-row-${baseProvider.id}`)
+    await user.click(within(row).getByRole('button', { name: /edit/i }))
+
     await user.click(screen.getByTestId('provider-test-btn'))
 
     await waitFor(() => {
@@ -582,6 +583,15 @@ describe('Notifications', () => {
     })
   })
 
+  it('disables test button when provider is new (unsaved) and not email type', async () => {
+    const user = userEvent.setup()
+    renderWithQueryClient(<Notifications />)
+
+    await user.click(await screen.findByTestId('add-provider-btn'))
+    const testBtn = screen.getByTestId('provider-test-btn')
+    expect(testBtn).toBeDisabled()
+  })
+
   it('shows JSON template selector for gotify provider', async () => {
     const user = userEvent.setup()
     renderWithQueryClient(<Notifications />)