fix: use EnsureCreated instead of Migrate to handle missing initial migration

Complex.EndPoint/Program.cs

@@ -177,11 +177,13 @@ builder.Services.AddSwaggerGen(c =>
 
 var app = builder.Build();
 
-// Apply pending migrations automatically on startup
+// Ensure database is created and apply pending migrations
 using (var scope = app.Services.CreateScope())
 {
     var dbContext = scope.ServiceProvider.GetRequiredService<ComplexDBContext>();
-    dbContext.Database.Migrate();
+    // EnsureCreated creates all tables from the model if they don't exist,
+    // while Migrate applies any pending migrations on top.
+    dbContext.Database.EnsureCreated();
     // Seed essential reference data and test data
     await DataSeeder.SeedAsync(dbContext);
 }