feat(ui): Mission Control Recent Sessions mit verschachtelten Handoffs

Neue Tabelle mission_control_sessions (Migration AddMissionControlSessions), befuellt vom
InteractiveLaunchSpecService bei Task-, Ad-hoc- und Handoff-Kacheln. Flyout im Mission-Control-Header
listet die letzten 14 Tage / 50 Sessions, Handoffs eingerueckt unter ihrer Ursprungs-Session, mit
Fortsetzen (--resume im gespeicherten cwd) und Brief anzeigen.

src/ClaudeDo.Worker/Hub/WorkerHub.cs

@@ -798,6 +798,14 @@ public sealed class WorkerHub : Microsoft.AspNetCore.SignalR.Hub
         return _interactiveLaunchSpec.BuildHandoffAsync(paneId, cwd, briefPath, taskId, Context.ConnectionAborted);
     });
 
+    /// <summary>Launch spec resuming a recorded Mission Control session ("Recent sessions") in a new tile.</summary>
+    public Task<LaunchSpec> GetResumeSessionLaunchSpec(string sessionId, string paneId) => HubGuard(() =>
+    {
+        if (_interactiveLaunchSpec is null)
+            throw new InvalidOperationException("Interactive launch spec service is not configured.");
+        return _interactiveLaunchSpec.BuildResumeAsync(sessionId, paneId, Context.ConnectionAborted);
+    });
+
     // Builds the launch spec for an embedded ConPTY "merge helper" session that drives the given
     // tasks to a merged/Done state via the mcp__claudedo__* tools. listId scopes the brief label
     // and cwd to that list. handlerTaskId is the id returned by CreateMergeHelperTask -- it is