feat(worker): in-app interactive session service, replacing the wt terminal launch

InteractiveSessionService resolves a task's list working dir + seeded prompt,
spawns a StreamingClaudeSession (claude stream-json in the list dir, model+auto
as before), registers it in LiveSessionRegistry, streams output over TaskMessage,
and broadcasts InteractiveSessionStarted/Ended (an exit watcher fires Ended). The
hub's OpenInteractiveTerminalAsync now starts this in-app session; SendInteractiveMessage
and StopInteractiveSession route to it. The external Windows-Terminal interactive
launch (LaunchInteractiveAsync / InteractiveLaunchContext / OpenInteractiveAsync) is
removed; planning sessions keep their terminal launch.

src/ClaudeDo.Worker/Planning/PlanningSessionManager.cs

@@ -1,5 +1,4 @@
 using System.Security.Cryptography;
-using System.Text;
 using System.Text.Json;
 using ClaudeDo.Data;
 using ClaudeDo.Data.Git;
@@ -161,40 +160,6 @@ public sealed class PlanningSessionManager
             Files: files);
     }
 
-    public async Task<InteractiveLaunchContext> OpenInteractiveAsync(string taskId, CancellationToken ct)
-    {
-        var (tasks, lists, _, ctx) = CreateRepos();
-        await using var __ = ctx;
-
-        var task = await tasks.GetByIdAsync(taskId, ct)
-            ?? throw new InvalidOperationException($"Task {taskId} not found.");
-
-        var list = await lists.GetByIdAsync(task.ListId, ct)
-            ?? throw new InvalidOperationException($"List {task.ListId} not found.");
-
-        var workingDir = list.WorkingDir;
-        if (string.IsNullOrWhiteSpace(workingDir) || !Directory.Exists(workingDir))
-            throw new InvalidOperationException(
-                $"List '{list.Name}' has no valid working directory configured.");
-
-        return new InteractiveLaunchContext(
-            TaskId: taskId,
-            WorkingDir: workingDir,
-            InitialPrompt: BuildInteractivePrompt(task));
-    }
-
-    private static string BuildInteractivePrompt(TaskEntity task)
-    {
-        var sb = new StringBuilder();
-        sb.AppendLine($"# Task: {task.Title}");
-        if (!string.IsNullOrWhiteSpace(task.Description))
-        {
-            sb.AppendLine();
-            sb.AppendLine(task.Description);
-        }
-        return sb.ToString();
-    }
-
     public async Task<int> FinalizeAsync(string taskId, bool queueAgentTasks, CancellationToken ct)
     {
         var (tasks, lists, settings, ctx) = CreateRepos();