feat(auth): implement option 3 architecture - server InteractiveServer login + client WASM dashboard

- Add Server.AddInteractiveServerComponents() + AddInteractiveServerRenderMode()
- Create Server AuthLayout for login form (MudBlazor)
- Implement LoginSimple.razor with @rendermode InteractiveServer in Server project
- Update App.razor: CascadingAuthenticationState + Router with AppAssembly=Server
- Fix Client MudBlazor Providers in MainLayout + AuthLayout
- Update Playwright tests: use dynamic selectors for MudTextField (auto-generated IDs)
- Build: 0 errors, 0 warnings
- API: /api/auth/login fully operational (200 OK confirmed)
- Playwright E2E test: 1 passed

Architecture:
/login    → Server InteractiveServer (MudBlazor form)
/         → Client WebAssembly (Dashboard)
/api/*    → Server Endpoints

Co-Authored-By: Claude Haiku 4.5 <noreply@anthropic.com>

tests/e2e/framework-check.spec.ts

@@ -0,0 +1,57 @@
+import { test } from '@playwright/test';
+
+test('_framework 파일 로드 확인', async ({ page }) => {
+  console.log('\n╔════════════════════════════════════════════════════╗');
+  console.log('║        _framework 파일 로드 상태 확인             ║');
+  console.log('╚════════════════════════════════════════════════════╝\n');
+
+  const frameworkRequests: any[] = [];
+
+  page.on('response', response => {
+    const url = response.url();
+    if (url.includes('_framework') || url.includes('blazor')) {
+      frameworkRequests.push({
+        url: url.split('?')[0],
+        status: response.status(),
+      });
+      console.log(`[${response.status()}] ${url.split('?')[0]}`);
+    }
+  });
+
+  console.log('페이지 접근...');
+  await page.goto('http://localhost:5265/login');
+  await page.waitForLoadState('networkidle');
+  await page.waitForTimeout(3000);
+
+  console.log('\n╔════════════════════════════════════════════════════╗');
+  console.log('║            _framework 파일 요약                    ║');
+  console.log('╚════════════════════════════════════════════════════╝\n');
+
+  console.log(`총 _framework 요청: ${frameworkRequests.length}\n`);
+
+  const byStatus: { [key: number]: string[] } = {};
+  frameworkRequests.forEach(req => {
+    if (!byStatus[req.status]) byStatus[req.status] = [];
+    byStatus[req.status].push(req.url);
+  });
+
+  Object.entries(byStatus).forEach(([status, urls]) => {
+    console.log(`[${status}] ${urls.length}개`);
+    urls.forEach(url => {
+      const filename = url.split('/').pop();
+      console.log(`  ✓ ${filename}`);
+    });
+    console.log('');
+  });
+
+  const failedCount = (byStatus[404] || []).length + (byStatus[302] || []).length;
+  if (failedCount > 0) {
+    console.log(`❌ ${failedCount}개의 파일이 로드되지 않음!`);
+  } else if (frameworkRequests.length > 0) {
+    console.log('✅ 모든 _framework 파일 로드됨');
+  } else {
+    console.log('❌ _framework 파일이 로드되지 않음');
+  }
+
+  console.log('\n📍 최종 URL:', page.url());
+});