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/Data/WeatherForecastService.cs

@@ -0,0 +1,19 @@
+namespace TaxBaik.Admin.Data;
+
+public class WeatherForecastService
+{
+    private static readonly string[] Summaries = new[]
+    {
+        "Freezing", "Bracing", "Chilly", "Cool", "Mild", "Warm", "Balmy", "Hot", "Sweltering", "Scorching"
+    };
+
+    public Task<WeatherForecast[]> GetForecastAsync(DateOnly startDate)
+    {
+        return Task.FromResult(Enumerable.Range(1, 5).Select(index => new WeatherForecast
+        {
+            Date = startDate.AddDays(index),
+            TemperatureC = Random.Shared.Next(-20, 55),
+            Summary = Summaries[Random.Shared.Next(Summaries.Length)]
+        }).ToArray());
+    }
+}