fix: set input-blocking nil on input window so agent responses render

Croatoan child windows don't inherit the screen's :input-blocking nil.
Without explicit (setf (input-blocking iw) nil), get-char blocks the
main loop indefinitely, preventing redraw from running. New agent
messages queued by the reader-loop thread were never rendered until
the user pressed a key.

Now the loop runs at 30fps and responses appear immediately.

lisp/gateway-tui-main.lisp

@@ -235,10 +235,11 @@
            (ch (- h 5))
            (cw (make-instance 'window :height ch :width (- w 2) :y 3 :x 1))
            (iw (make-instance 'window :height 1 :width (- w 2) :y (- h 1) :x 1))
-           (swank-port (or (ignore-errors
-                             (parse-integer (uiop:getenv "TUI_SWANK_PORT")))
-                           4006)))
+            (swank-port (or (ignore-errors
+                              (parse-integer (uiop:getenv "TUI_SWANK_PORT")))
+                            4006)))
        (setf (function-keys-enabled-p iw) t
+             (input-blocking iw) nil
              (st :dirty) (list t t t))
        (connect-daemon)
        (when (> swank-port 0)