fix: add /eval back to /help listing — resolves flake

test-on-key-help checked for /eval in help output. The rewritten
help list dropped /eval which is still a working command. Fixed by
adding it as the first entry.

TUI Main: 98/98

org/channel-tui-main.org

@@ -370,6 +370,7 @@ Event handlers + daemon I/O + main loop.
                    (let ((topic (string-trim '(#\Space) (subseq text 6))))
                      (add-msg :system (format nil "Topic: ~a — use read-file to query USER_MANUAL.org" topic))))
                   ((string-equal text "/help")
+                   (add-msg :system "/eval <expr>   Evaluate Lisp")
                    (add-msg :system "/undo          Undo last operation")
                    (add-msg :system "/redo          Redo last operation")
                    (add-msg :system "/why           Show last gate trace")