fix: restructure let* closing so cat-proc stays in scope

sleep had 3 closers (sleep, loop, let*), closing the let* before
terminate-process. Reduced to 2 closers, added let* close after
terminate-process.

org/channel-tui-main.org

@@ -1020,11 +1020,11 @@ Event handlers + daemon I/O + main loop.
                                                           (sel-p (theme-color :accent))
                                                           (t (theme-color :agent-fg)))
                                                    nil :bold sel-p)
-                           (incf y-off)))))))
-               (sleep 0.1)))
-            (uiop:terminate-process cat-proc)
+                            (incf y-off)))))))
+               (sleep 0.1))
+            (uiop:terminate-process cat-proc))
             (add-msg :system (format nil "* cat ~a ended *" (uiop:process-info-pid cat-proc))))
-         (progn (disconnect-daemon))))
+          (progn (disconnect-daemon))))
 #+END_SRC
 
 * Test Suite