Separate QuantEngine database deployment

src/dotnet/QuantEngine.Web/Program.cs

@@ -46,8 +46,16 @@ builder.Services.AddAuthorizationCore();
 builder.Services.AddMudServices();
 
 // PostgreSQL Dapper Setup
-var connectionString = builder.Configuration.GetConnectionString("DefaultConnection")
-    ?? "Host=127.0.0.1;Database=giteadb;Username=gitea;Password=C8RFlZ9fdQrBA1vyLhLDS4v70I8dJfRS2ERJW4+zsS4=;Search Path=quantengine;";
+var configuredConnectionString = builder.Configuration.GetConnectionString("DefaultConnection");
+var fallbackConnectionString = "Host=127.0.0.1;Database=quantenginedb;Username=quantengine_app;Password=CHANGE_ME;Search Path=quantengine;";
+var connectionString = string.IsNullOrWhiteSpace(configuredConnectionString) || configuredConnectionString.Contains("Password=;", StringComparison.OrdinalIgnoreCase)
+    ? fallbackConnectionString
+    : configuredConnectionString;
+var configuredDatabase = new Npgsql.NpgsqlConnectionStringBuilder(connectionString).Database;
+if (!string.Equals(configuredDatabase, "quantenginedb", StringComparison.OrdinalIgnoreCase))
+{
+    throw new InvalidOperationException("QuantEngine must use the quantenginedb PostgreSQL database.");
+}
 builder.Services.AddSingleton<IDbConnectionFactory>(new DbConnectionFactory(connectionString));
 builder.Services.AddSingleton<DbMigrator>();
 builder.Services.AddScoped<IWorkspaceRepository, WorkspaceRepository>();