playwright: fix invitation-accepted toast text + SSO existing-account redirect

The bundled web vault renames the org-invitation-acceptance toast from
"Invitation accepted" to "Successfully accepted your invitation" in the
post-MP-unlock flow used by both invited-with-new-account and
invited-with-existing-account tests. Update both specs to match the new
toast text.

The SSO-side logNewUser flow still emits "Invitation accepted" for the
SSO account-creation toast, so setups/sso.ts is left untouched.

The SSO invited-with-existing-account flow also no longer auto-redirects
to Keycloak — existing emails land on the email-prefilled login form and
require an explicit "Use single sign-on" click. Add it before the
Keycloak heading assertion.

playwright/tests/organization.smtp.spec.ts

@@ -67,7 +67,7 @@ test('invited with new account', async ({ page }) => {
         await page.getByRole('button', { name: 'Create account' }).click();
         await utils.checkNotification(page, 'Your new account has been created');
 
-        await utils.checkNotification(page, 'Invitation accepted');
+        await utils.checkNotification(page, 'Successfully accepted your invitation');
         await utils.ignoreExtension(page);
 
         // Redirected to the vault
@@ -98,7 +98,7 @@ test('invited with existing account', async ({ page }) => {
     await page.getByLabel('Master password').fill(users.user3.password);
     await page.getByRole('button', { name: 'Log in with master password' }).click();
 
-    await utils.checkNotification(page, 'Invitation accepted');
+    await utils.checkNotification(page, 'Successfully accepted your invitation');
     await utils.ignoreExtension(page);
 
     // We are now in the default vault page

playwright/tests/sso_organization.smtp.spec.ts

@@ -98,6 +98,9 @@ test('invited with existing account', async ({ page }) => {
 
     await test.step('Redirect to Keycloak', async () => {
         await page.goto(link);
+        // Existing accounts land on the email-prefilled login form rather
+        // than auto-redirecting; click through to Keycloak explicitly.
+        await page.getByRole('button', { name: 'Use single sign-on' }).click();
     });
 
     await test.step('Keycloak login', async () => {
@@ -112,7 +115,7 @@ test('invited with existing account', async ({ page }) => {
         await page.getByLabel('Master password').fill(users.user3.password);
         await page.getByRole('button', { name: 'Unlock' }).click();
 
-        await utils.checkNotification(page, 'Invitation accepted');
+        await utils.checkNotification(page, 'Successfully accepted your invitation');
         await utils.ignoreExtension(page);
     });