fix(db): EF migration AddPrimaryBackupDataConnections

Captures the pre-existing entity drift from commit 04af039 (rename
Configuration to PrimaryConfiguration, add BackupConfiguration and
FailoverRetryCount), which was committed without a corresponding
migration. Generating this here unblocks the upcoming AddTemplateFolders
migration on the templates-folder-hierarchy branch.

src/ScadaLink.ConfigurationDatabase/Migrations/20260511144149_AddPrimaryBackupDataConnections.cs

@@ -0,0 +1,50 @@
+using Microsoft.EntityFrameworkCore.Migrations;
+
+#nullable disable
+
+namespace ScadaLink.ConfigurationDatabase.Migrations
+{
+    /// <inheritdoc />
+    public partial class AddPrimaryBackupDataConnections : Migration
+    {
+        /// <inheritdoc />
+        protected override void Up(MigrationBuilder migrationBuilder)
+        {
+            migrationBuilder.RenameColumn(
+                name: "Configuration",
+                table: "DataConnections",
+                newName: "PrimaryConfiguration");
+
+            migrationBuilder.AddColumn<string>(
+                name: "BackupConfiguration",
+                table: "DataConnections",
+                type: "nvarchar(4000)",
+                maxLength: 4000,
+                nullable: true);
+
+            migrationBuilder.AddColumn<int>(
+                name: "FailoverRetryCount",
+                table: "DataConnections",
+                type: "int",
+                nullable: false,
+                defaultValue: 3);
+        }
+
+        /// <inheritdoc />
+        protected override void Down(MigrationBuilder migrationBuilder)
+        {
+            migrationBuilder.DropColumn(
+                name: "BackupConfiguration",
+                table: "DataConnections");
+
+            migrationBuilder.DropColumn(
+                name: "FailoverRetryCount",
+                table: "DataConnections");
+
+            migrationBuilder.RenameColumn(
+                name: "PrimaryConfiguration",
+                table: "DataConnections",
+                newName: "Configuration");
+        }
+    }
+}

src/ScadaLink.ConfigurationDatabase/Migrations/ScadaLinkDbContextModelSnapshot.cs

@@ -17,7 +17,7 @@ namespace ScadaLink.ConfigurationDatabase.Migrations
         {
 #pragma warning disable 612, 618
             modelBuilder
-                .HasAnnotation("ProductVersion", "10.0.5")
+                .HasAnnotation("ProductVersion", "10.0.7")
                 .HasAnnotation("Relational:MaxIdentifierLength", 128);
 
             SqlServerModelBuilderExtensions.UseIdentityColumns(modelBuilder);
@@ -752,15 +752,24 @@ namespace ScadaLink.ConfigurationDatabase.Migrations
 
                     SqlServerPropertyBuilderExtensions.UseIdentityColumn(b.Property<int>("Id"));
 
-                    b.Property<string>("Configuration")
+                    b.Property<string>("BackupConfiguration")
                         .HasMaxLength(4000)
                         .HasColumnType("nvarchar(4000)");
 
+                    b.Property<int>("FailoverRetryCount")
+                        .ValueGeneratedOnAdd()
+                        .HasColumnType("int")
+                        .HasDefaultValue(3);
+
                     b.Property<string>("Name")
                         .IsRequired()
                         .HasMaxLength(200)
                         .HasColumnType("nvarchar(200)");
 
+                    b.Property<string>("PrimaryConfiguration")
+                        .HasMaxLength(4000)
+                        .HasColumnType("nvarchar(4000)");
+
                     b.Property<string>("Protocol")
                         .IsRequired()
                         .HasMaxLength(50)