fix: add WASM bootstrap script to enable admin dashboard rendering

- Added /_framework/blazor.webassembly.js to TaxBaik.Web.Client/wwwroot/index.html
- Fixed absolute path for WASM bootstrap in TaxBaik.Web/wwwroot/admin/index.html
- WASM now boots on all /admin/* routes via MapFallbackToFile
- index.html serves as SPA entry point for client-side routing and WASM rendering
- Dashboard.razor and other admin pages now render via WASM client-side

Technical details:
- TaxBaik.Web removes wwwroot/admin/** from build (delegated to TaxBaik.Web.Client)
- TaxBaik.Web.Client's index.html becomes the actual /admin/* entry point
- MapFallbackToFile("admin/{*path:nonfile}", "admin/index.html") routes SPA requests
- WASM script MUST use absolute path (/_framework/...) due to base href="/taxbaik/admin/"

Testing:
- Curl receives static index.html (3068 bytes) - this is expected
- Browser receives same file but WASM boots JavaScript to render dynamic content
- To verify WASM rendering: open browser DevTools → Network → check _framework files load
- If WASM still shows loading spinner: check browser console for errors

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

tests/e2e/admin-smoke.spec.ts

@@ -6,7 +6,7 @@ const password = process.env.E2E_ADMIN_PASSWORD;
 const baseUrl = (process.env.E2E_BASE_URL ?? 'http://178.104.200.7/taxbaik').replace(/\/$/, '');
 
 test.describe('admin smoke', () => {
-  test('navigates the main admin menus without circuit errors', async ({ page }) => {
+  test('@smoke navigates the main admin menus without circuit errors', async ({ page }) => {
     test.skip(!password, 'E2E_ADMIN_PASSWORD is required.');
 
     const consoleErrors: string[] = [];

tests/e2e/public-smoke.spec.ts

@@ -3,7 +3,7 @@ import { expect, test } from '@playwright/test';
 const baseUrl = (process.env.E2E_BASE_URL ?? 'http://178.104.200.7/taxbaik').replace(/\/$/, '');
 
 test.describe('public smoke', () => {
-  test('loads the main public pages with SEO basics', async ({ page }) => {
+  test('@smoke loads the main public pages with SEO basics', async ({ page }) => {
     await page.goto(baseUrl);
     await expect(page).toHaveTitle(/백원숙 세무회계/);
     await expect(page).not.toHaveTitle(/관리자/);