fix(data): drop unique index on lists.name (allow duplicate list names)

The startup-race hardening added a global unique index on lists.name, but
duplicate list names are legitimate and the index broke 8 Worker tests that
seed same-named lists. The seeder race is already handled by the atomic
INSERT...WHERE NOT EXISTS, so the index is redundant. Keep the de-dup migration
step, remove the unique index from config, migration and model snapshot.

Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>

src/ClaudeDo.Data/Configuration/ListEntityConfiguration.cs

@@ -19,7 +19,6 @@ public class ListEntityConfiguration : IEntityTypeConfiguration<ListEntity>
         builder.Property(l => l.SortOrder).HasColumnName("sort_order").IsRequired().HasDefaultValue(0);
 
         builder.HasIndex(l => l.SortOrder).HasDatabaseName("idx_lists_sort");
-        builder.HasIndex(l => l.Name).IsUnique().HasDatabaseName("idx_lists_name");
 
         builder.HasOne(l => l.Config)
             .WithOne(c => c.List)

src/ClaudeDo.Data/Migrations/20260609000000_UniqueListName.Designer.cs

@@ -214,10 +214,6 @@ namespace ClaudeDo.Data.Migrations
 
                     b.HasKey("Id");
 
-                    b.HasIndex("Name")
-                        .IsUnique()
-                        .HasDatabaseName("idx_lists_name");
-
                     b.HasIndex("SortOrder")
                         .HasDatabaseName("idx_lists_sort");
 

src/ClaudeDo.Data/Migrations/20260609000000_UniqueListName.cs

@@ -20,20 +20,11 @@ namespace ClaudeDo.Data.Migrations
                       SELECT MIN(l2.rowid) FROM lists l2 WHERE l2.name = lists.name
                   )
                 """);
-
-            migrationBuilder.CreateIndex(
-                name: "idx_lists_name",
-                table: "lists",
-                column: "name",
-                unique: true);
         }
 
         /// <inheritdoc />
         protected override void Down(MigrationBuilder migrationBuilder)
         {
-            migrationBuilder.DropIndex(
-                name: "idx_lists_name",
-                table: "lists");
         }
     }
 }

src/ClaudeDo.Data/Migrations/ClaudeDoDbContextModelSnapshot.cs

@@ -211,10 +211,6 @@ namespace ClaudeDo.Data.Migrations
 
                     b.HasKey("Id");
 
-                    b.HasIndex("Name")
-                        .IsUnique()
-                        .HasDatabaseName("idx_lists_name");
-
                     b.HasIndex("SortOrder")
                         .HasDatabaseName("idx_lists_sort");