adding complete db migrations from posgres

Backend/ERPCore/Program.cs

@@ -17,9 +17,7 @@ using ERPCore.System.Errors;
 using Microsoft.AspNetCore.Authentication;
 using Microsoft.AspNetCore.Authorization;
 using Microsoft.EntityFrameworkCore;
-using Microsoft.EntityFrameworkCore.Diagnostics;
 using Microsoft.OpenApi;
-using Npgsql;
 using Serilog;
 
 var builder = WebApplication.CreateBuilder(args);
@@ -33,11 +31,17 @@ builder.Host.UseSerilog((ctx, cfg) => cfg
 builder.Services.AddControllers()
     .AddJsonOptions(o => o.JsonSerializerOptions.Converters.Add(new JsonStringEnumConverter()));
 
-// EF Core + PostgreSQL
+// EF Core + MariaDB (Pomelo). The server version is pinned explicitly rather than using
+// ServerVersion.AutoDetect: AutoDetect opens a connection, which would make design-time
+// commands (`dotnet ef migrations add`) and startup depend on the database being reachable.
+// MariaDbServerVersion — not MySqlServerVersion — because the target is MariaDB 10.11, and
+// Pomelo changes its SQL translation based on which it is given.
+var connectionString = builder.Configuration.GetConnectionString("DefaultConnection")
+    ?? throw new InvalidOperationException("ConnectionStrings:DefaultConnection is not configured.");
+
 builder.Services.AddDbContext<ErpDbContext>(o =>
 {
-    o.UseNpgsql(builder.Configuration.GetConnectionString("DefaultConnection"));
-    o.ConfigureWarnings(w => w.Ignore(RelationalEventId.PendingModelChangesWarning));
+    o.UseMySql(connectionString, new MariaDbServerVersion(new Version(10, 11, 15)));
 });
 
 // ProblemDetails (RFC 7807) + domain-exception mapping