OPC # 0001: Extract Clarity into standalone repo

Clarity.MigrationService/Program.cs

@@ -0,0 +1,16 @@
+using Clarity.MigrationService;
+using Clarity.Server.Data;
+using Microsoft.EntityFrameworkCore;
+
+var builder = Host.CreateApplicationBuilder(args);
+builder.AddServiceDefaults();
+builder.Services.AddHostedService<Worker>();
+
+var connectionString = builder.Configuration.GetConnectionString("postgresdb")
+    ?? throw new InvalidOperationException("Connection string 'postgresdb' not found.");
+
+builder.Services.AddDbContext<ApplicationDbContext>(options =>
+    options.UseNpgsql(connectionString));
+
+var host = builder.Build();
+host.Run();