refactor(data): centralize list seeding in MigrateAndConfigure, add default-value test

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

src/ClaudeDo.Installer/Steps/InitDatabaseStep.cs

@@ -1,5 +1,4 @@
 using ClaudeDo.Data;
-using ClaudeDo.Data.Seeding;
 using ClaudeDo.Installer.Core;
 using Microsoft.EntityFrameworkCore;
 
@@ -21,7 +20,6 @@ public sealed class InitDatabaseStep : IInstallStep
                 .Options;
             using var context = new ClaudeDoDbContext(options);
             ClaudeDoDbContext.MigrateAndConfigure(context);
-            DefaultListsSeeder.SeedAsync(context).GetAwaiter().GetResult();
 
             progress.Report("Schema applied successfully");
             return Task.FromResult(StepResult.Ok());