fix: distribute-sizes rounding remainder, render-screen uses backend-size

src/components/render.lisp

@@ -32,9 +32,9 @@
 (defun render-screen (root backend)
   "Render the component tree ROOT using BACKEND.
   Computes layout for dirty branches, calls render on each component,
-  and wraps output in synchronized updates."
-  (let ((w (available-width root))
-        (h (available-height root)))
+  and wraps output in synchronized updates. Uses the actual terminal
+  dimensions from BACKEND rather than hardcoded defaults."
+  (multiple-value-bind (w h) (backend-size backend)
     (begin-sync backend)
     (render-node root backend w h)
     (end-sync backend)))