feat(worker,ui): wire EF Core into DI and update all consumers to IDbContextFactory

Worker and App Program.cs: replace SqliteConnectionFactory+SchemaInitializer
with AddDbContextFactory<ClaudeDoDbContext> + Database.Migrate(). Repos
changed from AddSingleton to AddScoped.

All singleton services (QueueService, StaleTaskRecovery, WorktreeManager,
TaskRunner) and singleton ViewModels (MainWindowViewModel, TaskDetailViewModel,
TaskListViewModel, TaskEditorViewModel) now take IDbContextFactory<ClaudeDoDbContext>
and create short-lived contexts per operation.

Test infrastructure: DbFixture now uses EF migrations instead of SchemaInitializer;
all test classes create contexts via DbFixture.CreateContext().

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

tests/ClaudeDo.Worker.Tests/Repositories/ListRepositoryConfigTests.cs

@@ -1,3 +1,4 @@
+using ClaudeDo.Data;
 using ClaudeDo.Data.Models;
 using ClaudeDo.Data.Repositories;
 using ClaudeDo.Worker.Tests.Infrastructure;
@@ -7,12 +8,14 @@ namespace ClaudeDo.Worker.Tests.Repositories;
 public sealed class ListRepositoryConfigTests : IDisposable
 {
     private readonly DbFixture _db = new();
+    private readonly ClaudeDoDbContext _ctx;
     private readonly ListRepository _repo;
     private readonly string _listId;
 
     public ListRepositoryConfigTests()
     {
-        _repo = new ListRepository(_db.Factory);
+        _ctx = _db.CreateContext();
+        _repo = new ListRepository(_ctx);
         _listId = Guid.NewGuid().ToString();
         _repo.AddAsync(new ListEntity
         {
@@ -57,5 +60,9 @@ public sealed class ListRepositoryConfigTests : IDisposable
         Assert.Equal("haiku-4-5", fetched.Model);
     }
 
-    public void Dispose() => _db.Dispose();
+    public void Dispose()
+    {
+        _ctx.Dispose();
+        _db.Dispose();
+    }
 }