Unify active task loading across API handlers

internal/server/images.go

@@ -23,13 +23,8 @@ var worktreeImageTypes = map[string]string{
 }
 
 func (s *Server) GetTaskImage(w http.ResponseWriter, r *http.Request, taskID string, params api.GetTaskImageParams) {
-	t, err := s.store.GetTask(r.Context(), taskID)
-	if err != nil {
-		writeStoreError(w, err)
-		return
-	}
-	if t.Status != api.TaskStatusActive {
-		writeError(w, http.StatusConflict, fmt.Errorf("task %s is %s and has no worktree", t.Id, t.Status))
+	t, ok := s.activeTask(w, r, taskID)
+	if !ok {
 		return
 	}