fix: add SIGWINCH resize handling for /dev/tty input path

Main loop now checks cl-tty.input::*terminal-resized-p* on every
iteration. When set (by SIGWINCH handler), re-queries backend-size
and marks all regions dirty for re-render.

org/channel-tui-main.org

@@ -925,6 +925,12 @@ Event handlers + daemon I/O + main loop.
                     (setf (st :connected) nil
                           (st :busy) nil)
                     (add-msg :system "* Connection lost — type /reconnect to retry *"))))
+               ;; Check for terminal resize (SIGWINCH sets this flag)
+               (when (boundp 'cl-tty.input::*terminal-resized-p*)
+                 (when cl-tty.input::*terminal-resized-p*
+                   (setf cl-tty.input::*terminal-resized-p* nil)
+                   (multiple-value-setq (w h) (cl-tty.backend:backend-size be))
+                   (setf (st :dirty) (list t t t))))
                ;; Read key input from /dev/tty (non-blocking)
                (let ((raw-ch (read-char-no-hang tty nil nil)))
                  (when raw-ch