fix: add draw-text method for raw 2D arrays

Application code (passepartout TUI) calls draw-text with a framebuffer
(2D array) as the first argument, but draw-text only had methods for
framebuffer-backend CLOS instances. Added a method on array that sets
cells directly on the framebuffer array, matching make-framebuffer's
return type.

src/rendering/framebuffer.lisp

@@ -76,7 +76,22 @@
         do (%set-cell fb (+ x i) y (char string i)
                       :fg fg :bg bg
                       :bold bold :italic italic :underline underline
-                      :link-url link-url)))
+                       :link-url link-url)))
+
+(defmethod draw-text ((fb array) x y string fg bg
+                      &key bold italic underline reverse dim blink
+                      &allow-other-keys)
+  (declare (ignore reverse dim blink))
+  (let ((h (array-dimension fb 0))
+        (w (array-dimension fb 1)))
+    (loop for i from 0 below (length string)
+          for cx from x
+          while (< cx w)
+          when (and (< y h) (>= cx 0) (>= y 0))
+          do (setf (aref fb y cx)
+                   (make-cell :char (char string i)
+                              :fg fg :bg bg
+                              :bold bold :italic italic :underline underline)))))
 
 (defmethod draw-rect ((fb framebuffer-backend) x y w h &key bg)
   (dotimes (row h)