Initial project setup: solution + 5 projects

- Domain, Infrastructure, Application (class libraries)
- Web (ASP.NET Core empty)
- Admin (Blazor Server)
- All net8.0 target framework
- Project references configured

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

TaxBaik.Admin/_Imports.razor

@@ -0,0 +1,10 @@
+@using System.Net.Http
+@using Microsoft.AspNetCore.Authorization
+@using Microsoft.AspNetCore.Components.Authorization
+@using Microsoft.AspNetCore.Components.Forms
+@using Microsoft.AspNetCore.Components.Routing
+@using Microsoft.AspNetCore.Components.Web
+@using Microsoft.AspNetCore.Components.Web.Virtualization
+@using Microsoft.JSInterop
+@using TaxBaik.Admin
+@using TaxBaik.Admin.Shared