feat(db): map TemplateFolder entity and Template.FolderId

src/ScadaLink.ConfigurationDatabase/Configurations/TemplateConfiguration.cs

@@ -26,6 +26,12 @@ public class TemplateConfiguration : IEntityTypeConfiguration<Template>
             .OnDelete(DeleteBehavior.Restrict)
             .IsRequired(false);
 
+        builder.HasOne<TemplateFolder>()
+            .WithMany()
+            .HasForeignKey(t => t.FolderId)
+            .OnDelete(DeleteBehavior.Restrict)
+            .IsRequired(false);
+
         builder.HasMany(t => t.Attributes)
             .WithOne()
             .HasForeignKey(a => a.TemplateId)
@@ -147,3 +153,24 @@ public class TemplateCompositionConfiguration : IEntityTypeConfiguration<Templat
         builder.HasIndex(c => new { c.TemplateId, c.InstanceName }).IsUnique();
     }
 }
+
+public class TemplateFolderConfiguration : IEntityTypeConfiguration<TemplateFolder>
+{
+    public void Configure(EntityTypeBuilder<TemplateFolder> builder)
+    {
+        builder.HasKey(f => f.Id);
+
+        builder.Property(f => f.Name)
+            .IsRequired()
+            .HasMaxLength(200);
+
+        builder.HasOne<TemplateFolder>()
+            .WithMany()
+            .HasForeignKey(f => f.ParentFolderId)
+            .OnDelete(DeleteBehavior.Restrict)
+            .IsRequired(false);
+
+        // Unique sibling name (case-insensitive enforced at service layer; this index is for fast lookup)
+        builder.HasIndex(f => new { f.ParentFolderId, f.Name }).IsUnique();
+    }
+}

src/ScadaLink.ConfigurationDatabase/ScadaLinkDbContext.cs

@@ -25,6 +25,7 @@ public class ScadaLinkDbContext : DbContext, IDataProtectionKeyContext
     public DbSet<TemplateAlarm> TemplateAlarms => Set<TemplateAlarm>();
     public DbSet<TemplateScript> TemplateScripts => Set<TemplateScript>();
     public DbSet<TemplateComposition> TemplateCompositions => Set<TemplateComposition>();
+    public DbSet<TemplateFolder> TemplateFolders => Set<TemplateFolder>();
 
     // Instances
     public DbSet<Instance> Instances => Set<Instance>();