fix: correct ASP.NET Core middleware order for WASM routing

Problem:
- UseBlazorFrameworkFiles/UseStaticFiles were AFTER Map* routes
- This caused 'request reached end of pipeline' 500 error

Solution:
- Move app.Use* (middleware) BEFORE app.Map* (routing)
- Blazor framework files now properly served at /admin/_framework
- Portal SPA fallback working correctly

Middleware order is critical:
1. app.Use* (processing order)
2. app.Map* (routing rules)
3. app.Run() (final endpoint)

Fixes: 500 error on /admin/_framework/blazor.webassembly.js

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

src/TaxBaik.Web/Program.cs

@@ -378,19 +378,19 @@ if (!app.Environment.IsDevelopment())
     app.UseHsts();
 }
 
-// API + Razor Pages + 정적 파일 매핑
+// Admin & Portal Blazor WebAssembly SPA 호스팅 (미들웨어 먼저!)
+app.UseBlazorFrameworkFiles("/admin");
+app.UseStaticFiles("/admin");
+app.UseBlazorFrameworkFiles("/portal");
+app.UseStaticFiles("/portal");
+
+// API + Razor Pages + 정적 파일 매핑 (라우팅은 나중에)
 app.MapControllers();
 app.MapFastEndpoints();
 app.MapHealthChecks("/healthz");
 app.MapRazorPages();
 app.MapStaticAssets();
 
-// Admin & Portal Blazor WebAssembly SPA 호스팅
-app.UseBlazorFrameworkFiles("/admin");
-app.UseStaticFiles("/admin");
-app.UseBlazorFrameworkFiles("/portal");
-app.UseStaticFiles("/portal");
-
 // SPA 라우팅 폴백 (각 경로에서 index.html 제공)
 app.MapFallbackToFile("admin/{*path:nonfile}", "admin/index.html");
 app.MapFallbackToFile("portal/{*path:nonfile}", "portal/index.html");