fix: add generate-tool-belt-prompt alias for cognitive-tool-prompt

Another naming drift: think() calls generate-tool-belt-prompt but the
actual function was cognitive-tool-prompt in core-defpackage.

lisp/core-defpackage.lisp

@@ -217,6 +217,10 @@
         (format nil "Available tools:~%~a" (apply #'concatenate 'string (sort descriptions #'string<)))
         "No tools registered.")))
 
+;; Alias: generate-tool-belt-prompt → cognitive-tool-prompt
+(defun generate-tool-belt-prompt ()
+  (cognitive-tool-prompt))
+
 (defun log-message (msg &rest args)
   "Centralized, thread-safe logging for the harness."
   (let ((formatted-msg (apply #'format nil msg args)))