Refactor(Structure): Move ADTs into adt/ folder, rename spel.rkt to main.rkt

New structure groups all ADT modules under adt/ directory, removing
redundant adt- prefix from filenames. Library names now read as
(pacman-project adt position) etc. All imports updated accordingly.

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

pacman-project/adt/pacman.rkt

@@ -0,0 +1,46 @@
+#lang r7rs
+
+;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
+;;                               Pac-Man ADT                                 ;;
+;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
+
+;; Manages the logical state of the player: grid position and current
+;; direction. Contains NO graphics code.
+
+(define-library (pacman-project adt pacman)
+  (import (scheme base)
+          (pacman-project adt position))
+  (export make-pacman)
+
+  (begin
+
+    ;; make-pacman :: number, number -> pacman
+    ;; Creates a Pac-Man object at the given start position (row, col).
+    (define (make-pacman start-row start-col)
+      (let ((position (make-position start-row start-col))
+            (direction 'right))
+
+        ;; position! :: position -> /
+        (define (position! new-position)
+          (set! position new-position))
+
+        ;; direction! :: symbol -> /
+        (define (direction! new-direction)
+          (set! direction new-direction))
+
+        ;; move! :: number, number -> /
+        ;; Moves Pac-Man by a delta on the grid.
+        (define (move! delta-row delta-col)
+          ((position 'row!) (+ (position 'row) delta-row))
+          ((position 'col!) (+ (position 'col) delta-col)))
+
+        ;; dispatch-pacman :: symbol -> any
+        (define (dispatch-pacman msg)
+          (cond ((eq? msg 'position) position)
+                ((eq? msg 'position!) position!)
+                ((eq? msg 'direction) direction)
+                ((eq? msg 'direction!) direction!)
+                ((eq? msg 'move!) move!)
+                (else (error "Pac-Man ADT -- Unknown message:" msg))))
+
+        dispatch-pacman))))