refactor: drop the remaining single-implementation interfaces

IBaseDirtyChecker, IInteractiveLaunchSpecService and the LaunchSpec wrapper
had one implementation and one caller each; ProcessRunnerAdapter existed only
to give a static class an interface, and InstallArtifactLocator used
inheritance for two constructor arguments. The external MCP container now
shares its singletons through a Share<T> helper instead of 17 near-identical
registrations.

src/ClaudeDo.Worker/State/TaskStateService.cs

@@ -18,7 +18,7 @@ public sealed class TaskStateService : ITaskStateService
     private readonly PlanningChainCoordinator _chain;
     private readonly RunCancellationRegistry _runCancels;
     private readonly Func<IActiveMergeState> _mergeState;
-    private readonly IBaseDirtyChecker _baseDirtyChecker;
+    private readonly BaseDirtyChecker _baseDirtyChecker;
     private readonly ILogger<TaskStateService> _logger;
 
     public TaskStateService(
@@ -28,7 +28,7 @@ public sealed class TaskStateService : ITaskStateService
         PlanningChainCoordinator chain,
         RunCancellationRegistry runCancels,
         Func<IActiveMergeState> mergeState,
-        IBaseDirtyChecker baseDirtyChecker,
+        BaseDirtyChecker baseDirtyChecker,
         ILogger<TaskStateService> logger)
     {
         _dbFactory = dbFactory;