feat(interactive): worker launch-spec for embedded ConPTY sessions

Adds InteractiveLaunchSpecService + GetInteractiveLaunchSpec hub method that
prepares a task worktree (session-skills seeding, run env) and returns a
LaunchSpec {cwd,exe,args,env} for a UI-hosted ConPTY terminal. Reuses
ISessionSkillSeeder, TaskRunner.UnionSkillNames, and WindowsTerminalLauncher
resume-arg/resolve logic. Guards mirror ResumeTaskInTerminal; a never-run task
yields a fresh-start spec instead of an error.

src/ClaudeDo.Ui/Services/WorkerClient.cs

@@ -564,6 +564,9 @@ public partial class WorkerClient : ObservableObject, IAsyncDisposable, IWorkerC
     public async Task ResumeTaskInTerminalAsync(string taskId, CancellationToken ct = default)
         => await _hub.InvokeAsync("ResumeTaskInTerminal", taskId, ct);
 
+    public async Task<LaunchSpec> GetInteractiveLaunchSpecAsync(string taskId, CancellationToken ct = default)
+        => await _hub.InvokeAsync<LaunchSpec>("GetInteractiveLaunchSpec", taskId, ct);
+
     public async Task<DiscardPlanningOutcome> DiscardPlanningSessionAsync(string taskId, bool dequeueQueuedChildren = false, CancellationToken ct = default)
         => await _hub.InvokeAsync<DiscardPlanningOutcome>("DiscardPlanningSessionAsync", taskId, dequeueQueuedChildren, ct);
 
@@ -677,6 +680,12 @@ public sealed record WorktreeOverviewDto(
     DateTime CreatedAt,
     bool PathExistsOnDisk);
 
+public sealed record LaunchSpec(
+    string Cwd,
+    string Exe,
+    IReadOnlyList<string> Args,
+    IReadOnlyDictionary<string, string> Env);
+
 public sealed record ForceRemoveResultDto(bool Removed, string? Reason);
 public sealed record PendingQuestionDto(string TaskId, string QuestionId, string Question);