[refactor] Replace PrimeVue ProgressSpinner with Lucide loader icon (#9372)

## Summary
- Replace PrimeVue `ProgressSpinner` with Lucide `loader-circle` icon in
App.vue and WorkspaceAuthGate.vue
- Use white color for loading spinner for better visibility on dark
backgrounds
- Remove `primevue/progressspinner` imports and update related test

## Changes
- **App.vue**: Replace `ProgressSpinner` with
`icon-[lucide--loader-circle]`
- **WorkspaceAuthGate.vue**: Same replacement
- **WorkspaceAuthGate.test.ts**: Remove ProgressSpinner mock, use
`.animate-spin` selector

## Review Focus
- Visual consistency of white spinner on dark background during initial
load

<img width="1596" height="1189" alt="스크린샷 2026-03-04 오후 6 28 27"
src="https://github.com/user-attachments/assets/d703db74-4123-4328-912a-45ac45cf6eeb"
/>
<img width="1680" height="1304" alt="스크린샷 2026-03-04 오후 6 28 24"
src="https://github.com/user-attachments/assets/8026d10a-7e06-4f95-849c-bc891756823c"
/>

┆Issue is synchronized with this [Notion
page](https://www.notion.so/PR-9372-refactor-Replace-PrimeVue-ProgressSpinner-with-Lucide-loader-icon-3196d73d3650815bb1d1d4554f7f744e)
by [Unito](https://www.unito.io)

src/platform/workspace/auth/WorkspaceAuthGate.test.ts

@@ -1,6 +1,7 @@
 import { flushPromises, mount } from '@vue/test-utils'
 import { beforeEach, describe, expect, it, vi } from 'vitest'
 import { ref } from 'vue'
+import { createI18n } from 'vue-i18n'
 
 import WorkspaceAuthGate from './WorkspaceAuthGate.vue'
 
@@ -50,10 +51,6 @@ vi.mock('@/platform/distribution/types', () => ({
   }
 }))
 
-vi.mock('primevue/progressspinner', () => ({
-  default: { template: '<div class="progress-spinner" />' }
-}))
-
 describe('WorkspaceAuthGate', () => {
   beforeEach(() => {
     vi.clearAllMocks()
@@ -66,8 +63,11 @@ describe('WorkspaceAuthGate', () => {
     mockWorkspaceStoreInitialize.mockResolvedValue(undefined)
   })
 
+  const i18n = createI18n({ legacy: false })
+
   const mountComponent = () =>
     mount(WorkspaceAuthGate, {
+      global: { plugins: [i18n] },
       slots: {
         default: '<div data-testid="slot-content">App Content</div>'
       }
@@ -81,7 +81,7 @@ describe('WorkspaceAuthGate', () => {
       await flushPromises()
 
       expect(wrapper.find('[data-testid="slot-content"]').exists()).toBe(true)
-      expect(wrapper.find('.progress-spinner').exists()).toBe(false)
+      expect(wrapper.find('[role="status"]').exists()).toBe(false)
       expect(mockRefreshRemoteConfig).not.toHaveBeenCalled()
     })
   })
@@ -92,7 +92,7 @@ describe('WorkspaceAuthGate', () => {
 
       const wrapper = mountComponent()
 
-      expect(wrapper.find('.progress-spinner').exists()).toBe(true)
+      expect(wrapper.find('[role="status"]').exists()).toBe(true)
       expect(wrapper.find('[data-testid="slot-content"]').exists()).toBe(false)
     })
 
@@ -100,7 +100,7 @@ describe('WorkspaceAuthGate', () => {
       mockIsInitialized.value = false
 
       const wrapper = mountComponent()
-      expect(wrapper.find('.progress-spinner').exists()).toBe(true)
+      expect(wrapper.find('[role="status"]').exists()).toBe(true)
 
       mockIsInitialized.value = true
       mockCurrentUser.value = null
@@ -180,7 +180,7 @@ describe('WorkspaceAuthGate', () => {
       await flushPromises()
 
       // Still showing spinner before timeout
-      expect(wrapper.find('.progress-spinner').exists()).toBe(true)
+      expect(wrapper.find('[role="status"]').exists()).toBe(true)
 
       // Advance past the 10 second timeout
       await vi.advanceTimersByTimeAsync(10_001)