fix(desktop/login): pass identifier alongside email and add phone to preview user

Aligns the desktop client with the server's phone-or-email login API so
sign-in works after the identifier-based auth switch.

apps/desktop-client/src/renderer/composables/useDesktopSession.ts

@@ -279,6 +279,7 @@ function createPreviewUser(): UserInfo {
   return {
     id: 0,
     email: "preview@geo-rankly.local",
+    phone: "",
     name: "开发预览账号",
     avatar_url: null,
     tenant_id: 0,

apps/desktop-client/src/renderer/views/LoginView.vue

@@ -57,6 +57,7 @@ async function submitLogin() {
   }
 
   await login({
+    identifier: form.email,
     email: form.email,
     password: form.password,
   });