fix: restore original text-input.lisp in org to fix handle-text-input

The tangled handle-text-input used (key-event-text event) for character
insertion, but the test suite creates key events with :code not :text.
Restored the original handle-text-input which uses
(code-char (key-event-code event)) — matching the test expectations.

tests/input-tests.lisp

@@ -386,3 +386,11 @@ world")))
   (remhash :local *keymaps*)
   (is-false (gethash :global *keymaps*))
   (is-false (gethash :local *keymaps*)))
+
+;; cleanup after keybinding tests
+(test keybinding-cleanup-global
+  "Clean up global keymap after testing."
+  (remhash :global *keymaps*)
+  (remhash :local *keymaps*)
+  (is-false (gethash :global *keymaps*))
+  (is-false (gethash :local *keymaps*)))