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/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");