feat(lists): assign a colour to a sidebar folder

Tints the folder name and its guide line; picked from a swatch row in the folder settings.

src/ClaudeDo.Data/Configuration/ListFolderEntityConfiguration.cs

@@ -15,6 +15,7 @@ public class ListFolderEntityConfiguration : IEntityTypeConfiguration<ListFolder
         builder.Property(f => f.Name).HasColumnName("name").IsRequired();
         builder.Property(f => f.CreatedAt).HasColumnName("created_at").IsRequired();
         builder.Property(f => f.Icon).HasColumnName("icon");
+        builder.Property(f => f.Color).HasColumnName("color");
         builder.Property(f => f.SortOrder).HasColumnName("sort_order").IsRequired().HasDefaultValue(0);
         builder.Property(f => f.IsCollapsed).HasColumnName("is_collapsed").IsRequired().HasDefaultValue(false);
         builder.Property(f => f.ParentFolderId).HasColumnName("parent_folder_id");

src/ClaudeDo.Data/Migrations/20260930080955_AddListFolderColor.cs

@@ -0,0 +1,28 @@
+using Microsoft.EntityFrameworkCore.Migrations;
+
+#nullable disable
+
+namespace ClaudeDo.Data.Migrations
+{
+    /// <inheritdoc />
+    public partial class AddListFolderColor : Migration
+    {
+        /// <inheritdoc />
+        protected override void Up(MigrationBuilder migrationBuilder)
+        {
+            migrationBuilder.AddColumn<string>(
+                name: "color",
+                table: "list_folders",
+                type: "TEXT",
+                nullable: true);
+        }
+
+        /// <inheritdoc />
+        protected override void Down(MigrationBuilder migrationBuilder)
+        {
+            migrationBuilder.DropColumn(
+                name: "color",
+                table: "list_folders");
+        }
+    }
+}

src/ClaudeDo.Data/Migrations/ClaudeDoDbContextModelSnapshot.cs

@@ -370,6 +370,10 @@ namespace ClaudeDo.Data.Migrations
                         .HasColumnType("TEXT")
                         .HasColumnName("id");
 
+                    b.Property<string>("Color")
+                        .HasColumnType("TEXT")
+                        .HasColumnName("color");
+
                     b.Property<DateTime>("CreatedAt")
                         .HasColumnType("TEXT")
                         .HasColumnName("created_at");

src/ClaudeDo.Data/Models/ListFolderEntity.cs

@@ -13,6 +13,8 @@ public sealed class ListFolderEntity
     public required DateTime CreatedAt { get; init; }
     // Icon key into the UI's icon library, same set as ListEntity.Icon; null = default folder icon.
     public string? Icon { get; set; }
+    /// <summary>Hex colour (#RRGGBB) for the sidebar name and guide line; null = theme default.</summary>
+    public string? Color { get; set; }
     public int SortOrder { get; set; }
     // Sidebar expand/collapse state. Lives here rather than in ui.config.json because the row is
     // already being read for the folder itself.

src/ClaudeDo.Data/Repositories/ListRepository.cs

@@ -109,16 +109,17 @@ public sealed class ListRepository
         await _context.SaveChangesAsync(ct);
     }
 
-    /// <summary>Patches just the two editable fields — a whole-entity Update would need
+    /// <summary>Patches just the editable fields — a whole-entity Update would need
     /// <c>CreatedAt</c>/<c>SortOrder</c>/<c>IsCollapsed</c> carried along and silently reset
     /// whichever the caller forgot (see the SetConfigAsync note in CLAUDE.md).</summary>
-    public async Task RenameFolderAsync(string folderId, string name, string? icon, CancellationToken ct = default)
+    public async Task RenameFolderAsync(string folderId, string name, string? icon, string? color, CancellationToken ct = default)
     {
         await _context.ListFolders
             .Where(f => f.Id == folderId)
             .ExecuteUpdateAsync(s => s
                 .SetProperty(f => f.Name, name)
-                .SetProperty(f => f.Icon, icon), ct);
+                .SetProperty(f => f.Icon, icon)
+                .SetProperty(f => f.Color, color), ct);
     }
 
     /// <summary>Deletes the folder only — its lists survive and fall back to the top level via