fix: add CSI positioning and ioctl sizing to simple-backend

- backend-size now uses TIOCGWINSZ ioctl (like modern-backend)
- draw-text adds \033[row;colH CSI cursor positioning
- draw-rect fills background with space characters at position
- draw-border uses CSI positioning instead of raw newlines+spaces
- Added cursor-hide/cursor-show, cursor-move, initialize/shutdown
- Detection: broader DA1 check (any ANSI response, not just kitty)
- Detection: added TERM-based fallback for modern terminal detection

src/backend/detection.lisp

@@ -31,13 +31,26 @@ TIMEOUT seconds. Returns the response string, or nil if no response."
       response)))
 
 (defun detect-backend-by-da1 ()
-  "Send DA1 (ESC[c) query and check for kitty terminal response code.
-Returns T if terminal reports kitty compatibility codes."
+  "Send DA1 (ESC[c) query and check for any terminal response.
+Returns T if the terminal responds to DA1 (indicating an ANSI-compatible terminal)."
   (let ((response (query-terminal (format nil "~C[c" (code-char 27)))))
     (when response
-      ;; DA1 response format: ESC [ ? digits ; digits c
-      ;; Kitty reports code 62 in the response
-      (search "?62" response))))
+      ;; Any DA1 response (ESC [ ? digits ... c) means the terminal
+      ;; understands ANSI escape sequences — good enough for modern-backend
+      (> (length response) 0))))
+
+(defun detect-backend-by-term ()
+  "Check TERM environment variable for modern terminal types.
+Returns :modern if TERM contains xterm, tmux, screen, kitty,
+alacritty, foot, wezterm, or ghostty."
+  (let ((term (sb-ext:posix-getenv "TERM")))
+    (when term
+      ;; Known non-modern terms
+      (unless (or (string-equal term "dumb")
+                  (string-equal term "dump")
+                  (string-equal term "emacs")
+                  (search "52" term))  ; VT52 — no ANSI
+        :modern))))
 
 (defun detect-backend ()
   "Auto-detect the appropriate backend for the current terminal.
@@ -47,6 +60,7 @@ Result is cached in *detected-backend* for subsequent calls."
       (setf *detected-backend*
             (if (and (detect-backend-by-tty)
                      (or (eql (detect-backend-by-env) :modern)
-                         (detect-backend-by-da1)))
+                         (detect-backend-by-da1)
+                         (eql (detect-backend-by-term) :modern)))
                 (make-modern-backend)
                 (make-simple-backend)))))