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>

src/ClaudeDo.Worker/Runner/WorktreeManager.cs

@@ -1,7 +1,9 @@
+using ClaudeDo.Data;
 using ClaudeDo.Data.Git;
 using ClaudeDo.Data.Models;
 using ClaudeDo.Data.Repositories;
 using ClaudeDo.Worker.Config;
+using Microsoft.EntityFrameworkCore;
 
 namespace ClaudeDo.Worker.Runner;
 
@@ -10,14 +12,14 @@ public sealed record WorktreeContext(string WorktreePath, string BranchName, str
 public sealed class WorktreeManager
 {
     private readonly GitService _git;
-    private readonly WorktreeRepository _wtRepo;
+    private readonly IDbContextFactory<ClaudeDoDbContext> _dbFactory;
     private readonly WorkerConfig _cfg;
     private readonly ILogger<WorktreeManager> _logger;
 
-    public WorktreeManager(GitService git, WorktreeRepository wtRepo, WorkerConfig cfg, ILogger<WorktreeManager> logger)
+    public WorktreeManager(GitService git, IDbContextFactory<ClaudeDoDbContext> dbFactory, WorkerConfig cfg, ILogger<WorktreeManager> logger)
     {
         _git = git;
-        _wtRepo = wtRepo;
+        _dbFactory = dbFactory;
         _cfg = cfg;
         _logger = logger;
     }
@@ -50,7 +52,9 @@ public sealed class WorktreeManager
         await _git.WorktreeAddAsync(workingDir, branchName, worktreePath, baseCommit, ct);
 
         // Insert worktrees row AFTER git succeeds — if git throws, no row is created.
-        await _wtRepo.AddAsync(new WorktreeEntity
+        using var context = _dbFactory.CreateDbContext();
+        var wtRepo = new WorktreeRepository(context);
+        await wtRepo.AddAsync(new WorktreeEntity
         {
             TaskId = task.Id,
             Path = worktreePath,
@@ -87,7 +91,9 @@ public sealed class WorktreeManager
         var head = await _git.RevParseHeadAsync(ctx.WorktreePath, ct);
         var diffStat = await _git.DiffStatAsync(ctx.WorktreePath, ctx.BaseCommit, head, ct);
 
-        await _wtRepo.UpdateHeadAsync(task.Id, head, diffStat, ct);
+        using var context = _dbFactory.CreateDbContext();
+        var wtRepo = new WorktreeRepository(context);
+        await wtRepo.UpdateHeadAsync(task.Id, head, diffStat, ct);
 
         _logger.LogInformation("Committed changes for task {TaskId}: {Head}", task.Id, head);
         return true;