refactor(ui): remove pick-up-in-terminal, keep ConPTY as the single session entry

Two context-menu entries opened a Claude session for the same task via different
mechanisms (embedded ConPTY vs. an external wt terminal). Drop the external-terminal
path entirely, including its worker hub method, launcher plumbing, and localization
keys, since the embedded ConPTY session already covers every case it did.

src/ClaudeDo.Worker/Planning/Interfaces/ITerminalLauncher.cs

@@ -7,10 +7,6 @@ public interface ITerminalLauncher
 {
     Task LaunchPlanningStartAsync(PlanningSessionStartContext ctx, CancellationToken cancellationToken);
     Task LaunchPlanningResumeAsync(PlanningSessionResumeContext ctx, CancellationToken cancellationToken);
-
-    // Resumes an arbitrary task's Claude session (--resume <id>) in a visible terminal so
-    // the user can pick up the conversation by hand — the "pick up in terminal" action.
-    Task LaunchResumeAsync(string workingDir, string claudeSessionId, CancellationToken cancellationToken);
 }
 
 public sealed class TerminalLaunchException : Exception