fix: add stty size subprocess fallback in both backends

stty size via uiop:run-program is the most reliable method —
it works from the shell on every Unix system and bypasses
alien/ioctl quirks. Placed between stdout ioctl and /dev/tty
ioctl in the fallback chain.

src/backend/modern.lisp

@@ -173,6 +173,19 @@ as a fallback when a keyword is not in *named-colors*.")
                  (values (sb-alien:deref winsize 1)  ;; cols
                          (sb-alien:deref winsize 0))) ;; rows
             (sb-alien:free-alien winsize))))
+      ;; stty size via subprocess — reliable on every Unix, bypasses
+      ;; SBCL's alien/ioctl quirks. Returns "ROWS COLS".
+      (ignore-errors
+        (let* ((out (uiop:run-program '("stty" "size")
+                                      :output :string
+                                      :ignore-error-status t))
+               (parts (and out (uiop:split-string
+                                 (string-trim '(#\newline #\space) out)))))
+          (when (and parts (= (length parts) 2))
+            (let ((rows (parse-integer (first parts) :junk-allowed t))
+                  (cols (parse-integer (second parts) :junk-allowed t)))
+              (when (and rows cols (> rows 0) (> cols 0))
+                (values cols rows))))))
       ;; Direct ioctl on /dev/tty — opens the real controlling terminal.
       (ignore-errors
         (let ((tty-fd (sb-unix:unix-open "/dev/tty" 0 0)))  ; O_RDONLY

src/backend/simple.lisp

@@ -34,6 +34,18 @@
                  (values (sb-alien:deref winsize 1)
                          (sb-alien:deref winsize 0)))
              (sb-alien:free-alien winsize))))
+      ;; stty size via subprocess — reliable on every Unix.
+      (ignore-errors
+        (let* ((out (uiop:run-program '("stty" "size")
+                                      :output :string
+                                      :ignore-error-status t))
+               (parts (and out (uiop:split-string
+                                 (string-trim '(#\newline #\space) out)))))
+          (when (and parts (= (length parts) 2))
+            (let ((rows (parse-integer (first parts) :junk-allowed t))
+                  (cols (parse-integer (second parts) :junk-allowed t)))
+              (when (and rows cols (> rows 0) (> cols 0))
+                (values cols rows))))))
       (ignore-errors
         (let ((tty-fd (sb-unix:unix-open "/dev/tty" 0 0)))  ; O_RDONLY
           (when (and tty-fd (numberp tty-fd) (> tty-fd 0))