fix: disable kitty keyboard, fix CSI parser crashes

- Disabled \033[?u kitty keyboard protocol in modern-backend
  (converts all keys to escape sequences, breaking Ctrl+letter dispatch)
- Fixed parse-csi-sequence: use multiple-value-bind instead of let*
  with destructuring-bind (lost secondary return value from read-param)
- Fixed parse-csi-params format string: pass char-code of terminator
  as distinct argument for ~d, keeping the character for ~C
- Added %query-terminal-size in classes.lisp: ANSI CSI 18t fallback
  for terminal size detection when ioctl fails or returns zero

src/backend/modern.lisp

@@ -127,14 +127,16 @@ as a fallback when a keyword is not in *named-colors*.")
   (backend-write b (format nil "~C[?1002h" #\Esc))  ; mouse drag
   (backend-write b (format nil "~C[?1006h" #\Esc))  ; SGR mouse
   (backend-write b (format nil "~C[?2004h" #\Esc))  ; bracketed paste
-  (backend-write b (format nil "~C[?u" #\Esc))      ; kitty keyboard
+  ;; Kitty keyboard protocol disabled — converts all keys to CSI u-sequences
+  ;; which the TUI's key mapping doesn't handle for Ctrl+letter combos.
+  ;; (backend-write b (format nil "~C[?u" #\Esc))
   (cursor-hide b)
   (finish-output (backend-output-stream b))
   b)
 
 (defmethod shutdown-backend ((b modern-backend))
   (cursor-show b)
-  (backend-write b (format nil "~C[?u" #\Esc))
+  ;; (backend-write b (format nil "~C[?u" #\Esc))  ; disabled — never enabled
   (backend-write b (format nil "~C[?2004l" #\Esc))
   (backend-write b (format nil "~C[?1006l" #\Esc))
   (backend-write b (format nil "~C[?1002l" #\Esc))
@@ -156,7 +158,7 @@ as a fallback when a keyword is not in *named-colors*.")
   (backend-write b (format nil "~C[?1002h" #\Esc))  ; mouse drag
   (backend-write b (format nil "~C[?1006h" #\Esc))  ; SGR mouse
   (backend-write b (format nil "~C[?2004h" #\Esc))  ; bracketed paste
-  (backend-write b (format nil "~C[?u" #\Esc))      ; kitty keyboard
+  ;; (backend-write b (format nil "~C[?u" #\Esc))    ; kitty keyboard — disabled
   (cursor-hide b)
   (finish-output (backend-output-stream b))
   (values))
@@ -173,6 +175,7 @@ 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))))
+      (%query-terminal-size)
       (values 80 24)))
 
 (defmethod backend-write ((b modern-backend) string)