refactor admin UX and stabilize shell

tests/e2e/login-test.spec.ts

@@ -2,8 +2,8 @@ import { expect, test } from '@playwright/test';
 import { captureEvidence } from './helpers/evidence';
 
 const baseUrl = (process.env.E2E_BASE_URL ?? 'https://www.taxbaik.com').replace(/\/$/, '');
-const username = 'admin';
-const password = 'Admin123!@#456';
+const username = process.env.E2E_ADMIN_USERNAME;
+const password = process.env.E2E_ADMIN_PASSWORD;
 
 test('Admin Login Page - prerendered HTML contains the form before JS runs', async ({ request }) => {
   // Login.razor is @rendermode ...(prerender: true), so the raw HTTP response
@@ -21,6 +21,7 @@ test('Admin Login Page - prerendered HTML contains the form before JS runs', asy
 });
 
 test('Admin Login Page - Full Flow Test', async ({ page }) => {
+  test.skip(!username || !password, 'E2E_ADMIN_USERNAME and E2E_ADMIN_PASSWORD are required.');
   // 콘솔 에러 캡처
   page.on('console', msg => {
     if (msg.type() === 'error') console.log('🔴 CONSOLE ERROR:', msg.text());