test: add vitest test infrastructure and configuration

- Add vitest.config.ts with coverage thresholds
- Add test/setup.ts with testing-library setup
- Add test/helpers.ts with test utilities

admin-web/test/setup.ts

@@ -0,0 +1,59 @@
+import '@testing-library/jest-dom'
+import { vi, beforeAll, afterAll, beforeEach } from 'vitest'
+
+// Check if we have test database credentials
+const hasTestDb = process.env.NEXT_PUBLIC_SUPABASE_URL && 
+                  (process.env.SUPABASE_SERVICE_ROLE_KEY || process.env.NEXT_PUBLIC_SUPABASE_ANON_KEY)
+
+// Global test setup
+beforeAll(async () => {
+  if (hasTestDb) {
+    console.log('🧪 Setting up test environment with real database...')
+    const testUrl = process.env.NEXT_PUBLIC_SUPABASE_URL
+    if (!testUrl?.includes('test') && !testUrl?.includes('localhost')) {
+      console.warn('⚠️  WARNING: Not using a test database!')
+      console.warn('Current URL:', testUrl)
+    }
+  } else {
+    console.log('🧪 Running tests with mocked database...')
+  }
+})
+
+beforeEach(async () => {
+  // Cleanup before each test to ensure isolation (only if we have real DB)
+  if (hasTestDb) {
+    try {
+      const { cleanupTestData } = await import('./helpers')
+      await cleanupTestData()
+    } catch (e) {
+      // Silently ignore if helpers not available
+    }
+  }
+})
+
+afterAll(async () => {
+  if (hasTestDb) {
+    console.log('🧹 Cleaning up test environment...')
+    try {
+      const { cleanupTestData } = await import('./helpers')
+      await cleanupTestData()
+    } catch (e) {
+      // Silently ignore if helpers not available
+    }
+  }
+})
+
+// Mock Supabase client for component tests that don't need real DB
+vi.mock('@/lib/supabase', () => ({
+  supabase: {
+    storage: {
+      from: vi.fn(() => ({
+        upload: vi.fn(),
+        remove: vi.fn(),
+        move: vi.fn(),
+        list: vi.fn(),
+        getPublicUrl: vi.fn(() => ({ data: { publicUrl: 'https://example.com/test.jpg' } })),
+      })),
+    },
+  },
+}))