fix: lower sidebar threshold to 60 cols, word-wrap agent messages

- Sidebar threshold lowered from 120 to 60 so it works on 83-col
  terminals
- Agent response text is now word-wrapped through cl-tty.box:word-wrap
  after markdown rendering, preventing text from bleeding past the
  terminal edge

org/channel-tui-main.org

@@ -1033,7 +1033,7 @@ Event handlers + daemon I/O + main loop.
                (cl-tty.backend:draw-text be 0 (- h 4) (make-string w :initial-element #\─)
                                          (theme-color :separator) nil)
                (view-input be w h)
-               (when (and (st :sidebar-visible) (>= w 120))
+               (when (and (st :sidebar-visible) (>= w 60))
                  (view-sidebar be w h))
                 (setf (st :dirty) (list nil nil nil)))
               (let ((ds (st :dialog-stack)))